Disk speed per drive: IOPS, MB/s and latency

- file-io records each file's drive: sys.dm_os_volume_stats from 2008 R2 SP1
  (new capability VolumeStats, mount points included), otherwise derived
  from the path (D:\..., \server\share\, / on Linux), so 2005 works too
- migration 0007: Volume and IntervalSeconds on FileIoSamples, and
  DiskHourly (rolled up by maintenance, kept HourlyDays)
- DiskActivity sums files per drive: read/write IOPS, MB/s and latency
  weighted by I/O count
- instance page: "Diskhastighed pr. drev" (table and MB/s + latency charts);
  time window analysis and its PDF: per drive against the same hours of the
  four previous weeks
- SQLI-IO-001/002 now report per drive (one finding when the storage is
  slow, the slowest files in the evidence) instead of per file

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/analyse.md

@@ -13,6 +13,7 @@ Angiv fra og til (i webbrugerfladens tidszone, `SQLInsight:Web:TimeZone`), eller
 | Belastning | Forløb af CPU (SQL Server og andre processer), batch requests og compilations pr. sekund, page life expectancy, brugerforbindelser, memory grants pending og blokerede processer |
 | Største ventetider | Ventetid pr. minut i tidsrummet, sammenlignet med normalen. Harmløse baggrundsventetider er udeladt |
 | Tungeste forespørgsler | De forespørgsler, der brugte mest CPU, tid, læsninger eller blev kørt flest gange i tidsrummet, med tekst og database |
+| Diskhastighed pr. drev | Læse- og skrive-IOPS, MB/s og gennemsnitlig latens pr. drev, sammenlignet med normalen (se nedenfor) |
 | I/O-latens pr. fil | Læsninger, skrivninger og gennemsnitlig latens pr. databasefil |
 | Blocking og deadlocks | Blocking-kæder over 5 sekunder (head blocker, antal blokerede, længste ventetid) og deadlocks med graf (.xdl) |
 | Fund | Fund, der var aktive på et tidspunkt i tidsrummet |
@@ -26,11 +27,22 @@ Kun tidsrum, hvor agenten kørte og data stadig er gemt:
 | Data | Opbevaring (standard, `SQLInsight:Retention`) |
 |---|---|
 | Målinger hvert 5. minut: belastning, ventetider, I/O, forespørgsler | 14 dage (`RawDays`) |
-| Timeværdier: belastning og ventetider | 400 dage (`HourlyDays`) |
+| Timeværdier: belastning, ventetider og diskhastighed pr. drev | 400 dage (`HourlyDays`) |
 | Blocking og deadlocks | 90 dage (`EventDays`) |
 
 Ligger tidsrummet længere tilbage end `RawDays`, bruges timeværdier. Det står på siden. Så er der ingen I/O pr. fil og ingen forespørgsler, men belastning og ventetider kan stadig sammenlignes.
 
+## Diskhastighed pr. drev
+
+Agenten læser hvert 5. minut, hvor meget hver databasefil har læst og skrevet (`sys.dm_io_virtual_file_stats`: antal I/O'er, bytes og ventetid), og lægger filerne sammen pr. drev:
+
+- **IOPS** = læsninger eller skrivninger pr. sekund, **MB/s** = data pr. sekund, **latens** = gennemsnitlig ventetid pr. læsning eller skrivning, vægtet efter antal I/O'er.
+- Drevet kommer fra `sys.dm_os_volume_stats` (SQL Server 2008 R2 SP1 og nyere), så mount points vises rigtigt. På ældre versioner udledes det af filens sti (`D:\…` → `D:\`), og et mount point under et drevbogstav tælles da med drevet.
+- Det er tal set fra SQL Server: kun SQL Servers egne filer, ikke andre programmer på samme drev.
+- Instanssiden viser de seneste 24 timer med graf over MB/s og latens pr. drev. Fundene SQLI-IO-001 (læselatens på datafiler) og SQLI-IO-002 (skrivelatens på logfiler) gælder pr. drev, med de langsomste filer som målinger.
+
+Et drev markeres med rødt, når datafiler har over 20 ms pr. læsning, logfiler over 5 ms pr. skrivning, eller latensen er mindst dobbelt så høj som normalt.
+
 ## Tungeste forespørgsler
 
 Agenten læser `sys.dm_exec_query_stats` hvert 5. minut (collector `query-stats`, kan ændres med `SQLInsight:CollectorIntervals`) og gemmer, hvad hver forespørgsel brugte siden sidst:

src/SQLInsight.Collectors/Performance/FileIoCollector.cs

@@ -8,12 +8,25 @@ public sealed class FileIoCollector : Collector<CumulativeSample<FileIoSnapshot,
     internal const string Sql = """
         SELECT DB_NAME(vfs.database_id), vfs.file_id, mf.type_desc, mf.physical_name,
                vfs.num_of_reads, vfs.num_of_bytes_read, vfs.io_stall_read_ms,
-               vfs.num_of_writes, vfs.num_of_bytes_written, vfs.io_stall_write_ms
+               vfs.num_of_writes, vfs.num_of_bytes_written, vfs.io_stall_write_ms,
+               CAST(NULL AS nvarchar(260))
         FROM sys.dm_io_virtual_file_stats(NULL, NULL) vfs
         JOIN sys.master_files mf ON mf.database_id = vfs.database_id AND mf.file_id = vfs.file_id
         WHERE mf.type_desc IN (N'ROWS', N'LOG')
         """;
 
+    /// <summary>With the real volume (mount points included), from 2008 R2 SP1.</summary>
+    internal const string SqlWithVolumes = """
+        SELECT DB_NAME(vfs.database_id), vfs.file_id, mf.type_desc, mf.physical_name,
+               vfs.num_of_reads, vfs.num_of_bytes_read, vfs.io_stall_read_ms,
+               vfs.num_of_writes, vfs.num_of_bytes_written, vfs.io_stall_write_ms,
+               vs.volume_mount_point
+        FROM sys.dm_io_virtual_file_stats(NULL, NULL) vfs
+        JOIN sys.master_files mf ON mf.database_id = vfs.database_id AND mf.file_id = vfs.file_id
+        OUTER APPLY sys.dm_os_volume_stats(vfs.database_id, vfs.file_id) vs
+        WHERE mf.type_desc IN (N'ROWS', N'LOG')
+        """;
+
     public override string Name => "file-io";
     public override TimeSpan DefaultInterval => TimeSpan.FromMinutes(5);
     public override IReadOnlyCollection<Capability> RequiredCapabilities => [Capability.DynamicManagementViews];
@@ -23,18 +36,24 @@ public sealed class FileIoCollector : Collector<CumulativeSample<FileIoSnapshot,
     {
         var ct = context.CancellationToken;
         var startTime = await Db.StartTimeAsync(context.Connection, context.Instance.Version, ct).ConfigureAwait(false);
-        var files = await Db.QueryAsync(context.Connection, Sql, r => new FileIoStat
+        var sql = context.Capabilities.Has(Capability.VolumeStats) ? SqlWithVolumes : Sql;
+        var files = await Db.QueryAsync(context.Connection, sql, r =>
         {
-            DatabaseName = r.NullableString(0) ?? "?",
+            var physicalName = r.String(3);
-            FileId = r.Int(1),
+            return new FileIoStat
-            FileType = r.String(2),
+            {
-            PhysicalName = r.String(3),
+                DatabaseName = r.NullableString(0) ?? "?",
-            Reads = r.Long(4),
+                FileId = r.Int(1),
-            BytesRead = r.Long(5),
+                FileType = r.String(2),
-            ReadStallMs = r.Long(6),
+                PhysicalName = physicalName,
-            Writes = r.Long(7),
+                Reads = r.Long(4),
-            BytesWritten = r.Long(8),
+                BytesRead = r.Long(5),
-            WriteStallMs = r.Long(9),
+                ReadStallMs = r.Long(6),
+                Writes = r.Long(7),
+                BytesWritten = r.Long(8),
+                WriteStallMs = r.Long(9),
+                Volume = r.NullableString(10) is { Length: > 0 } volume ? volume : DiskVolumes.FromPhysicalName(physicalName),
+            };
         }, ct).ConfigureAwait(false);
 
         var snapshot = new FileIoSnapshot { CapturedAt = context.Now, SqlServerStartTime = startTime, Files = files };

src/SQLInsight.Core/Data/FileIo.cs

@@ -19,6 +19,13 @@ public sealed record FileIoStat
     public required string FileType { get; init; }
 
     public required string PhysicalName { get; init; }
+
+    /// <summary>
+    /// The volume (drive or mount point) the file lives on, e.g. <c>D:\</c>. From <c>sys.dm_os_volume_stats</c> where
+    /// the instance has it, otherwise derived from the path (<see cref="DiskVolumes.FromPhysicalName"/>).
+    /// </summary>
+    public string? Volume { get; init; }
+
     public required long Reads { get; init; }
     public required long BytesRead { get; init; }
     public required long ReadStallMs { get; init; }
@@ -30,6 +37,69 @@ public sealed record FileIoStat
     public double? AverageWriteLatencyMs => Writes == 0 ? null : (double)WriteStallMs / Writes;
 }
 
+/// <summary>
+/// Which drive a database file is on, when SQL Server cannot say (before 2008 R2 SP1 there is no
+/// <c>sys.dm_os_volume_stats</c>).
+/// </summary>
+public static class DiskVolumes
+{
+    /// <summary>
+    /// <c>D:\Data\x.mdf</c> → <c>D:\</c>; <c>\\nas\sql\x.mdf</c> → <c>\\nas\sql\</c>; a Linux path → <c>/</c>. A mount point
+    /// under a drive letter cannot be told apart from the drive itself this way.
+    /// </summary>
+    public static string FromPhysicalName(string physicalName)
+    {
+        ArgumentNullException.ThrowIfNull(physicalName);
+        var path = physicalName.Trim();
+        if (path.Length >= 2 && char.IsAsciiLetter(path[0]) && path[1] == ':')
+        {
+            return char.ToUpperInvariant(path[0]) + @":\";
+        }
+
+        if (path.StartsWith(@"\\", StringComparison.Ordinal))
+        {
+            var parts = path[2..].Split('\\', StringSplitOptions.RemoveEmptyEntries);
+            return parts.Length >= 2 ? $@"\\{parts[0]}\{parts[1]}\" : path;
+        }
+
+        return path.StartsWith('/') ? "/" : path;
+    }
+
+    /// <summary>The file's volume as reported, or derived from its path.</summary>
+    public static string Of(FileIoStat file)
+    {
+        ArgumentNullException.ThrowIfNull(file);
+        return string.IsNullOrWhiteSpace(file.Volume) ? FromPhysicalName(file.PhysicalName) : file.Volume;
+    }
+}
+
+/// <summary>
+/// I/O on one drive over an interval: the sum of its database files. Latency is weighted by the number of I/Os.
+/// </summary>
+public sealed record DiskActivity(string Volume, int DataFiles, int LogFiles, long Reads, long Writes, long BytesRead, long BytesWritten,
+    long ReadStallMs, long WriteStallMs, double Seconds)
+{
+    public double? ReadIops => Seconds > 0 ? Reads / Seconds : null;
+    public double? WriteIops => Seconds > 0 ? Writes / Seconds : null;
+    public double? ReadMbPerSecond => Seconds > 0 ? BytesRead / 1048576.0 / Seconds : null;
+    public double? WriteMbPerSecond => Seconds > 0 ? BytesWritten / 1048576.0 / Seconds : null;
+    public double? AverageReadMs => Reads == 0 ? null : (double)ReadStallMs / Reads;
+    public double? AverageWriteMs => Writes == 0 ? null : (double)WriteStallMs / Writes;
+
+    /// <summary>Groups the files of one interval by drive.</summary>
+    public static IReadOnlyList<DiskActivity> ByVolume(IEnumerable<FileIoStat> files, double seconds)
+    {
+        ArgumentNullException.ThrowIfNull(files);
+        return files
+            .GroupBy(DiskVolumes.Of, StringComparer.OrdinalIgnoreCase)
+            .Select(g => new DiskActivity(g.Key, g.Count(f => f.FileType != "LOG"), g.Count(f => f.FileType == "LOG"),
+                g.Sum(f => f.Reads), g.Sum(f => f.Writes), g.Sum(f => f.BytesRead), g.Sum(f => f.BytesWritten),
+                g.Sum(f => f.ReadStallMs), g.Sum(f => f.WriteStallMs), seconds))
+            .OrderBy(d => d.Volume, StringComparer.OrdinalIgnoreCase)
+            .ToList();
+    }
+}
+
 /// <summary>
 /// I/O per file between two snapshots.
 /// </summary>

src/SQLInsight.Core/Instances/Capability.cs

@@ -64,4 +64,7 @@ public enum Capability
 
     /// <summary><c>sys.dm_exec_text_query_plan</c> (cached plans as text, per statement). SQL Server 2005 SP2+.</summary>
     TextQueryPlan,
+
+    /// <summary><c>sys.dm_os_volume_stats</c> and <c>sys.dm_server_services</c>. SQL Server 2008 R2 SP1+.</summary>
+    VolumeStats,
 }

src/SQLInsight.Core/Instances/InstanceCapabilities.cs

@@ -13,6 +13,7 @@ public sealed class InstanceCapabilities
             [Capability.DefaultTrace] = new(9, 0, 0, 0),
             [Capability.ViewServerStatePermission] = new(9, 0, 0, 0),
             [Capability.TextQueryPlan] = new(9, 0, 3042, 0), // 2005 SP2
+            [Capability.VolumeStats] = new(10, 50, 2500, 0), // 2008 R2 SP1
             [Capability.ExtendedEvents] = new(10, 0, 0, 0),
             [Capability.SystemHealthSession] = new(10, 0, 0, 0),
             [Capability.SystemHealthFileTarget] = new(11, 0, 0, 0),

src/SQLInsight.Reports/TimeWindow.cs

@@ -162,4 +162,38 @@ public static class WindowBaseline
         var values = earlierWeeks.SelectMany(w => w).Select(p => p.Value).ToList();
         return values.Count == 0 ? null : values.Average();
     }
+
+    /// <summary>
+    /// Each drive in the window against the same hours of earlier weeks: all earlier weeks' I/O pooled, so latency is
+    /// weighted by the number of I/Os and rates by the time measured.
+    /// </summary>
+    public static IReadOnlyList<DiskComparison> CompareDisks(IReadOnlyList<Core.Data.DiskActivity> window, IReadOnlyList<IReadOnlyList<Core.Data.DiskActivity>> earlierWeeks)
+    {
+        ArgumentNullException.ThrowIfNull(window);
+        ArgumentNullException.ThrowIfNull(earlierWeeks);
+        return window
+            .Select(d =>
+            {
+                var earlier = earlierWeeks.SelectMany(w => w).Where(e => string.Equals(e.Volume, d.Volume, StringComparison.OrdinalIgnoreCase)).ToList();
+                Core.Data.DiskActivity? normal = earlier.Count == 0 || earlier.Sum(e => e.Seconds) <= 0
+                    ? null
+                    : new Core.Data.DiskActivity(d.Volume, 0, 0, earlier.Sum(e => e.Reads), earlier.Sum(e => e.Writes), earlier.Sum(e => e.BytesRead),
+                        earlier.Sum(e => e.BytesWritten), earlier.Sum(e => e.ReadStallMs), earlier.Sum(e => e.WriteStallMs), earlier.Sum(e => e.Seconds));
+                return new DiskComparison(d, normal);
+            })
+            .ToList();
+    }
+}
+
+/// <summary>A drive's I/O in the window compared with the same hours of the week in the previous weeks.</summary>
+public sealed record DiskComparison(Core.Data.DiskActivity Window, Core.Data.DiskActivity? Normal)
+{
+    /// <summary>Data files over 20 ms per read or log files over 5 ms per write: slow whatever the history says.</summary>
+    public bool IsSlow => Window.AverageReadMs >= 20 && Window.Reads >= 100 || Window.AverageWriteMs >= (Window.DataFiles == 0 ? 5 : 20) && Window.Writes >= 100;
+
+    /// <summary>Latency at least twice the normal (and noticeably so), or a slow drive.</summary>
+    public bool IsUnusual => IsSlow
+        || Worse(Window.AverageReadMs, Normal?.AverageReadMs) || Worse(Window.AverageWriteMs, Normal?.AverageWriteMs);
+
+    private static bool Worse(double? now, double? normal) => now is { } n && normal is > 0 and var m && n >= m * 2 && n - m >= 2;
 }

src/SQLInsight.Reports/TimeWindowAnalysis.cs

@@ -16,6 +16,10 @@ public sealed record TimeWindowAnalysis
     public required IReadOnlyList<MetricComparison> Metrics { get; init; }
     public required IReadOnlyList<WaitComparison> Waits { get; init; }
     public required IReadOnlyList<FileLatency> Files { get; init; }
+
+    /// <summary>Disk speed per drive, against the normal for the same hours.</summary>
+    public IReadOnlyList<DiskComparison> Disks { get; init; } = [];
+
     public required IReadOnlyList<StoredBlocking> Blocking { get; init; }
     public required IReadOnlyList<StoredDeadlock> Deadlocks { get; init; }
     public required IReadOnlyList<StoredFinding> Findings { get; init; }
@@ -24,7 +28,7 @@ public sealed record TimeWindowAnalysis
     /// <summary>The heaviest statements. Their text is customer data: only for the local UI and PDF.</summary>
     public required IReadOnlyList<TopQuery> TopQueries { get; init; }
 
-    public bool HasData => Metrics.Any(m => m.Points.Count > 0) || Waits.Count > 0 || Files.Count > 0 || Blocking.Count > 0
+    public bool HasData => Metrics.Any(m => m.Points.Count > 0) || Waits.Count > 0 || Files.Count > 0 || Disks.Count > 0 || Blocking.Count > 0
                            || Deadlocks.Count > 0 || TopQueries.Count > 0;
 
     /// <summary>The metrics shown, in order: key, label, unit, decimals, lower-is-worse, fixed maximum.</summary>
@@ -80,11 +84,17 @@ public sealed record TimeWindowAnalysis
         }
 
         var earlierWaits = new List<IReadOnlyList<HourlyWaitTotal>>();
+        var earlierDisks = new List<IReadOnlyList<Core.Data.DiskActivity>>();
         foreach (var back in weeks)
         {
             earlierWaits.Add(await repository.GetWaitsHourlyAsync(id, from - back, to - back, cancellationToken).ConfigureAwait(false));
+            earlierDisks.Add(await repository.GetDiskActivityHourlyAsync(id, from - back, to - back, cancellationToken).ConfigureAwait(false));
         }
 
+        var windowDisks = resolution == WindowResolution.Raw
+            ? await repository.GetDiskActivityAsync(id, from, to, cancellationToken).ConfigureAwait(false)
+            : await repository.GetDiskActivityHourlyAsync(id, from, to, cancellationToken).ConfigureAwait(false);
+
         return new TimeWindowAnalysis
         {
             Instance = instance,
@@ -95,6 +105,7 @@ public sealed record TimeWindowAnalysis
             Metrics = metrics,
             Waits = WindowBaseline.CompareWaits(windowWaits, minutes, earlierWaits),
             Files = await repository.GetFileLatencyAsync(id, from, to, cancellationToken).ConfigureAwait(false),
+            Disks = WindowBaseline.CompareDisks(windowDisks, earlierDisks),
             Blocking = await repository.GetBlockingAsync(id, from, to, cancellationToken).ConfigureAwait(false),
             Deadlocks = await repository.GetDeadlocksAsync(id, from, to, cancellationToken).ConfigureAwait(false),
             Findings = await repository.GetFindingsActiveDuringAsync(id, from, to, cancellationToken).ConfigureAwait(false),

src/SQLInsight.Reports/TimeWindowReport.cs

@@ -65,6 +65,7 @@ public static class TimeWindowReport
         Metrics(section, analysis);
         Waits(section, analysis);
         TopQueries(section, analysis);
+        Disks(section, analysis);
         Files(section, analysis);
         Blocking(section, analysis, zone);
         Deadlocks(section, analysis, zone);
@@ -144,6 +145,29 @@ public static class TimeWindowReport
         }
     }
 
+    private static void Disks(Section section, TimeWindowAnalysis analysis)
+    {
+        section.AddParagraph("Diskhastighed pr. drev", StyleNames.Heading1);
+        if (analysis.Disks.Count == 0)
+        {
+            section.AddParagraph("Ingen målinger pr. drev i tidsrummet (indsamles fra version 1.0.5).", "Muted");
+            return;
+        }
+
+        var table = Table(section, [3.2, 2.2, 2.2, 2.2, 2.2, 2.6, 2.8]);
+        Header(table, "Drev", "Læs IOPS", "Skriv IOPS", "Læs MB/s", "Skriv MB/s", "Gns. læs", "Gns. skriv");
+        foreach (var d in analysis.Disks)
+        {
+            var w = d.Window;
+            Row(table, d.IsUnusual, w.Volume, Number(w.ReadIops, 1), Number(w.WriteIops, 1), Number(w.ReadMbPerSecond, 1), Number(w.WriteMbPerSecond, 1),
+                Ms(w.AverageReadMs) + Normal(d.Normal?.AverageReadMs), Ms(w.AverageWriteMs) + Normal(d.Normal?.AverageWriteMs));
+        }
+
+        section.AddParagraph("Latens i parentes: det normale for samme klokkeslæt de foregående uger.", "Muted");
+
+        static string Normal(double? value) => value is { } v ? $" ({v.ToString("N1", Danish)})" : "";
+    }
+
     private static void Files(Section section, TimeWindowAnalysis analysis)
     {
         section.AddParagraph("I/O-latens pr. fil", StyleNames.Heading1);

src/SQLInsight.Repository/InsightRepository.Disks.cs

@@ -0,0 +1,63 @@
+using Dapper;
+using SQLInsight.Core.Data;
+
+namespace SQLInsight.Repository;
+
+/// <summary>Throughput and latency of one drive over time, for the charts.</summary>
+public sealed record DiskSeries(string Volume, IReadOnlyList<MetricPoint> MbPerSecond, IReadOnlyList<MetricPoint> LatencyMs);
+
+public sealed partial class InsightRepository
+{
+    /// <summary>
+    /// I/O per drive in [from, to], from the 5-minute samples. Each sample's interval counts once per drive, so IOPS and
+    /// MB/s are averages over the time actually measured. Samples from before disk speed was collected have no drive.
+    /// </summary>
+    public async Task<IReadOnlyList<DiskActivity>> GetDiskActivityAsync(int instanceId, DateTimeOffset from, DateTimeOffset to, CancellationToken cancellationToken = default)
+    {
+        await using var connection = await OpenAsync(cancellationToken).ConfigureAwait(false);
+        var rows = await connection.QueryAsync<(string Volume, int DataFiles, int LogFiles, long Reads, long Writes, long BytesRead, long BytesWritten, long ReadStallMs, long WriteStallMs, int Seconds)>("""
+            SELECT Volume, MAX(DataFiles), MAX(LogFiles), SUM(Reads), SUM(Writes), SUM(BytesRead), SUM(BytesWritten), SUM(ReadStallMs), SUM(WriteStallMs), SUM(Seconds)
+            FROM (
+                SELECT Volume, SampledAt,
+                       COUNT(CASE WHEN FileType <> 'LOG' THEN 1 END) AS DataFiles, COUNT(CASE WHEN FileType = 'LOG' THEN 1 END) AS LogFiles,
+                       SUM(Reads) AS Reads, SUM(Writes) AS Writes, SUM(BytesRead) AS BytesRead, SUM(BytesWritten) AS BytesWritten,
+                       SUM(ReadStallMs) AS ReadStallMs, SUM(WriteStallMs) AS WriteStallMs, MAX(IntervalSeconds) AS Seconds
+                FROM insight.FileIoSamples
+                WHERE InstanceId = @instanceId AND SampledAt > @from AND SampledAt <= @to AND Volume IS NOT NULL AND IntervalSeconds IS NOT NULL
+                GROUP BY Volume, SampledAt
+            ) AS samples
+            GROUP BY Volume ORDER BY Volume;
+            """, new { instanceId, from = from.UtcDateTime, to = to.UtcDateTime }).ConfigureAwait(false);
+        return rows.Select(r => new DiskActivity(r.Volume, r.DataFiles, r.LogFiles, r.Reads, r.Writes, r.BytesRead, r.BytesWritten, r.ReadStallMs, r.WriteStallMs, r.Seconds)).ToList();
+    }
+
+    /// <summary>I/O per drive from the hourly history for the hours overlapping [from, to).</summary>
+    public async Task<IReadOnlyList<DiskActivity>> GetDiskActivityHourlyAsync(int instanceId, DateTimeOffset from, DateTimeOffset to, CancellationToken cancellationToken = default)
+    {
+        await using var connection = await OpenAsync(cancellationToken).ConfigureAwait(false);
+        var rows = await connection.QueryAsync<(string Volume, long Reads, long Writes, long BytesRead, long BytesWritten, long ReadStallMs, long WriteStallMs, int Seconds)>("""
+            SELECT Volume, SUM(Reads), SUM(Writes), SUM(BytesRead), SUM(BytesWritten), SUM(ReadStallMs), SUM(WriteStallMs), SUM(Seconds)
+            FROM insight.DiskHourly WHERE InstanceId = @instanceId AND [Hour] >= @from AND [Hour] < @to
+            GROUP BY Volume ORDER BY Volume;
+            """, new { instanceId, from = FloorHour(from), to = to.UtcDateTime }).ConfigureAwait(false);
+        return rows.Select(r => new DiskActivity(r.Volume, 0, 0, r.Reads, r.Writes, r.BytesRead, r.BytesWritten, r.ReadStallMs, r.WriteStallMs, r.Seconds)).ToList();
+    }
+
+    /// <summary>MB/s (read + write) and average latency per drive per sample since <paramref name="from"/>.</summary>
+    public async Task<IReadOnlyList<DiskSeries>> GetDiskSeriesAsync(int instanceId, DateTimeOffset from, CancellationToken cancellationToken = default)
+    {
+        await using var connection = await OpenAsync(cancellationToken).ConfigureAwait(false);
+        var rows = await connection.QueryAsync<(string Volume, DateTime SampledAt, long Ios, long Bytes, long StallMs, int Seconds)>("""
+            SELECT Volume, SampledAt, SUM(Reads + Writes), SUM(BytesRead + BytesWritten), SUM(ReadStallMs + WriteStallMs), MAX(IntervalSeconds)
+            FROM insight.FileIoSamples
+            WHERE InstanceId = @instanceId AND SampledAt >= @from AND Volume IS NOT NULL AND IntervalSeconds IS NOT NULL
+            GROUP BY Volume, SampledAt ORDER BY Volume, SampledAt;
+            """, new { instanceId, from = from.UtcDateTime }).ConfigureAwait(false);
+        return rows.GroupBy(r => r.Volume)
+            .Select(g => new DiskSeries(
+                g.Key,
+                g.Where(r => r.Seconds > 0).Select(r => new MetricPoint(r.SampledAt, r.Bytes / 1048576.0 / r.Seconds)).ToList(),
+                g.Where(r => r.Ios > 0).Select(r => new MetricPoint(r.SampledAt, (double)r.StallMs / r.Ios)).ToList()))
+            .ToList();
+    }
+}

src/SQLInsight.Repository/InsightRepository.Maintenance.cs

@@ -53,6 +53,24 @@ public sealed partial class InsightRepository
             ) AS s ON t.InstanceId = s.InstanceId AND t.[Hour] = s.[Hour] AND t.WaitType = s.WaitType
             WHEN MATCHED THEN UPDATE SET WaitingTasks = s.WaitingTasks, WaitTimeMs = s.WaitTimeMs, SignalWaitTimeMs = s.SignalWaitTimeMs
             WHEN NOT MATCHED THEN INSERT (InstanceId, [Hour], WaitType, WaitingTasks, WaitTimeMs, SignalWaitTimeMs) VALUES (s.InstanceId, s.[Hour], s.WaitType, s.WaitingTasks, s.WaitTimeMs, s.SignalWaitTimeMs);
+
+            MERGE insight.DiskHourly AS t
+            USING (
+                SELECT InstanceId, [Hour], Volume, SUM(Reads) AS Reads, SUM(Writes) AS Writes, SUM(BytesRead) AS BytesRead, SUM(BytesWritten) AS BytesWritten,
+                       SUM(ReadStallMs) AS ReadStallMs, SUM(WriteStallMs) AS WriteStallMs, SUM(Seconds) AS Seconds
+                FROM (
+                    SELECT InstanceId, DATEADD(hour, DATEDIFF(hour, 0, SampledAt), 0) AS [Hour], Volume, SampledAt,
+                           SUM(Reads) AS Reads, SUM(Writes) AS Writes, SUM(BytesRead) AS BytesRead, SUM(BytesWritten) AS BytesWritten,
+                           SUM(ReadStallMs) AS ReadStallMs, SUM(WriteStallMs) AS WriteStallMs, MAX(IntervalSeconds) AS Seconds
+                    FROM insight.FileIoSamples WHERE SampledAt >= @from AND Volume IS NOT NULL AND IntervalSeconds IS NOT NULL
+                    GROUP BY InstanceId, Volume, SampledAt
+                ) AS samples
+                GROUP BY InstanceId, [Hour], Volume
+            ) AS s ON t.InstanceId = s.InstanceId AND t.[Hour] = s.[Hour] AND t.Volume = s.Volume
+            WHEN MATCHED THEN UPDATE SET Reads = s.Reads, Writes = s.Writes, BytesRead = s.BytesRead, BytesWritten = s.BytesWritten,
+                ReadStallMs = s.ReadStallMs, WriteStallMs = s.WriteStallMs, Seconds = s.Seconds
+            WHEN NOT MATCHED THEN INSERT (InstanceId, [Hour], Volume, Reads, Writes, BytesRead, BytesWritten, ReadStallMs, WriteStallMs, Seconds)
+                VALUES (s.InstanceId, s.[Hour], s.Volume, s.Reads, s.Writes, s.BytesRead, s.BytesWritten, s.ReadStallMs, s.WriteStallMs, s.Seconds);
             """, new { from }, commandTimeout: 600).ConfigureAwait(false);
 
         var raw = utc.AddDays(-options.RawDays);
@@ -67,6 +85,7 @@ public sealed partial class InsightRepository
         await DeleteInBatchesAsync(connection, "insight.QueryTexts", "LastSeenAt < @cutoff", raw).ConfigureAwait(false);
         await DeleteInBatchesAsync(connection, "insight.MetricHourly", "[Hour] < @cutoff", hourly).ConfigureAwait(false);
         await DeleteInBatchesAsync(connection, "insight.WaitHourly", "[Hour] < @cutoff", hourly).ConfigureAwait(false);
+        await DeleteInBatchesAsync(connection, "insight.DiskHourly", "[Hour] < @cutoff", hourly).ConfigureAwait(false);
         await DeleteInBatchesAsync(connection, "insight.BlockingEvents", "SampledAt < @cutoff", events).ConfigureAwait(false);
         await DeleteInBatchesAsync(connection, "insight.Deadlocks", "OccurredAt < @cutoff", events).ConfigureAwait(false);
         await DeleteInBatchesAsync(connection, "insight.Findings", "ResolvedAt < @cutoff", resolved).ConfigureAwait(false);

src/SQLInsight.Repository/InsightRepository.cs

@@ -279,12 +279,18 @@ public sealed partial class InsightRepository(string connectionString)
 
     private static Task<int> SaveFileIoAsync(SqlConnection connection, int instanceId, FileIoDelta delta) =>
         connection.ExecuteAsync("""
-            INSERT insight.FileIoSamples (InstanceId, SampledAt, DatabaseName, FileId, FileType, Reads, ReadStallMs, Writes, WriteStallMs, BytesRead, BytesWritten)
+            INSERT insight.FileIoSamples (InstanceId, SampledAt, DatabaseName, FileId, FileType, Reads, ReadStallMs, Writes, WriteStallMs, BytesRead, BytesWritten, Volume, IntervalSeconds)
-            SELECT @instanceId, @at, DatabaseName, FileId, FileType, Reads, ReadStallMs, Writes, WriteStallMs, BytesRead, BytesWritten
+            SELECT @instanceId, @at, DatabaseName, FileId, FileType, Reads, ReadStallMs, Writes, WriteStallMs, BytesRead, BytesWritten, Volume, @interval
             FROM OPENJSON(@json) WITH (DatabaseName nvarchar(128), FileId int, FileType varchar(10), Reads bigint, ReadStallMs bigint,
-                                       Writes bigint, WriteStallMs bigint, BytesRead bigint, BytesWritten bigint) j
+                                       Writes bigint, WriteStallMs bigint, BytesRead bigint, BytesWritten bigint, Volume nvarchar(260)) j
             WHERE NOT EXISTS (SELECT 1 FROM insight.FileIoSamples f WHERE f.InstanceId = @instanceId AND f.SampledAt = @at AND f.DatabaseName = j.DatabaseName AND f.FileId = j.FileId);
-            """, new { instanceId, at = Utc(delta.To), json = JsonSerializer.Serialize(delta.Files, Json) });
+            """, new
+        {
+            instanceId,
+            at = Utc(delta.To),
+            interval = (int)Math.Round((delta.To - delta.From).TotalSeconds),
+            json = JsonSerializer.Serialize(delta.Files.Select(f => f with { Volume = DiskVolumes.Of(f) }), Json),
+        });
 
     private static Task<int> InsertMetricsAsync(SqlConnection connection, int instanceId, IEnumerable<(string Metric, DateTimeOffset At, double Value)> metrics) =>
         connection.ExecuteAsync("""

src/SQLInsight.Repository/Migrations/0007_disk_volumes.sql

@@ -0,0 +1,21 @@
+/* Disk speed per drive: which volume each file sample belongs to, and how long the sample interval was (for IOPS and
+   MB/s). NULL on samples taken before this version. */
+ALTER TABLE insight.FileIoSamples ADD Volume nvarchar(260) NULL, IntervalSeconds int NULL;
+GO
+
+/* Hourly I/O per drive, kept as long as the other hourly aggregates (Retention:HourlyDays). Seconds = the measured
+   time within the hour, so rates stay right when samples are missing. */
+CREATE TABLE insight.DiskHourly
+(
+    InstanceId      int NOT NULL,
+    [Hour]          datetime2(0) NOT NULL,
+    Volume          nvarchar(260) NOT NULL,
+    Reads           bigint NOT NULL,
+    Writes          bigint NOT NULL,
+    BytesRead       bigint NOT NULL,
+    BytesWritten    bigint NOT NULL,
+    ReadStallMs     bigint NOT NULL,
+    WriteStallMs    bigint NOT NULL,
+    Seconds         int NOT NULL,
+    CONSTRAINT PK_DiskHourly PRIMARY KEY (InstanceId, [Hour], Volume)
+);

src/SQLInsight.Rules/Performance/ResourceRules.cs

@@ -14,65 +14,97 @@ internal static class FileIo
 }
 
 /// <summary>
-/// Slow reads from data files.
+/// Slow reads from the data files on a drive. Per drive rather than per file: when storage is slow, every file on it
+/// is, and one finding per drive says so once. The slowest files are in the evidence.
 /// </summary>
 public sealed class DataFileReadLatencyRule : Rule
 {
     public const int MinReads = 1000;
 
     public override string Id => "SQLI-IO-001";
-    public override string Title => "Høj læselatens på datafiler";
+    public override string Title => "Høj læselatens på drev med datafiler";
     public override IReadOnlyCollection<Capability> RequiredCapabilities => [Capability.DynamicManagementViews];
 
     public override RuleEvaluation Evaluate(RuleContext context)
     {
         ArgumentNullException.ThrowIfNull(context);
         var delta = FileIo.Delta(context);
+        var seconds = (delta.To - delta.From).TotalSeconds;
         return Result(delta.Files
-            .Where(f => f.FileType == "ROWS" && f.Reads >= MinReads && f.AverageReadLatencyMs >= 20)
+            .Where(f => f.FileType == "ROWS")
-            .Select(f => CreateFinding(
+            .GroupBy(DiskVolumes.Of, StringComparer.OrdinalIgnoreCase)
-                f.AverageReadLatencyMs >= 50 ? Severity.High : Severity.Medium,
+            .Select(g => (Files: g.ToList(), Disk: DiskActivity.ByVolume(g, seconds)[0]))
-                $"{f.DatabaseName}: {Format.Number(f.AverageReadLatencyMs!.Value, 1)} ms i gennemsnit pr. læsning",
+            .Where(d => d.Disk.Reads >= MinReads && d.Disk.AverageReadMs >= 20)
-                "Læsninger fra datafilen tager i gennemsnit over 20 ms. På moderne storage (SSD/SAN) bør de ligge under 5-10 ms. "
+            .Select(d => CreateFinding(
-                + "Langsomme læsninger rammer direkte alle forespørgsler, der ikke finder data i buffer pool.",
+                d.Disk.AverageReadMs >= 50 ? Severity.High : Severity.Medium,
+                $"{d.Disk.Volume} (datafiler): {Format.Number(d.Disk.AverageReadMs!.Value, 1)} ms i gennemsnit pr. læsning",
+                "Læsninger fra datafilerne på drevet tager i gennemsnit over 20 ms. På moderne storage (SSD/SAN) bør de ligge under "
+                + "5-10 ms. Langsomme læsninger rammer direkte alle forespørgsler, der ikke finder data i hukommelsen (buffer pool), "
+                + "så brugerne oplever langsomme skærmbilleder og rapporter.",
                 "Sammenlign med latensen i storage-laget (Windows' Avg. Disk sec/Read, SAN-statistik) for at se, om ventetiden "
-                + "opstår i storage eller undervejs (HBA, multipath, VM-host). Undersøg også, om mængden af læsninger kan reduceres "
+                + "opstår i storage eller undervejs (HBA, multipath, VM-host). Ser storage-laget hurtigt ud, er drevet overbelastet "
-                + "med bedre indexes eller mere hukommelse.",
+                + "af antallet af læsninger: se læse-IOPS og MB/s, og undersøg om de kan reduceres med bedre indexes eller mere hukommelse.",
-                [new Evidence("Fil", f.PhysicalName), new Evidence("Læsninger", Format.Number(f.Reads)),
+                Evidence(d.Disk, d.Files, read: true, seconds),
-                 new Evidence("Gns. latens", $"{Format.Number(f.AverageReadLatencyMs!.Value, 1)} ms"),
+                subject: $"volume: {d.Disk.Volume} data",
-                 new Evidence("Interval", $"{Format.Number((delta.To - delta.From).TotalMinutes)} min")],
-                subject: $"file: {f.DatabaseName}/{f.FileId}",
                 references: Docs.Learn("sys.dm_io_virtual_file_stats", "relational-databases/system-dynamic-management-views/sys-dm-io-virtual-file-stats-transact-sql"))));
     }
+
+    /// <summary>Drive totals plus the three slowest files, shared with the log write rule.</summary>
+    internal static Evidence[] Evidence(DiskActivity disk, IReadOnlyList<FileIoStat> files, bool read, double seconds)
+    {
+        var slowest = files
+            .Where(f => read ? f.Reads > 0 : f.Writes > 0)
+            .OrderByDescending(f => read ? f.AverageReadLatencyMs : f.AverageWriteLatencyMs)
+            .Take(3)
+            .Select(f => $"{f.DatabaseName} {Format.Number((read ? f.AverageReadLatencyMs : f.AverageWriteLatencyMs)!.Value, 1)} ms ({f.PhysicalName})");
+        return read
+            ?
+            [
+                new("Drev", disk.Volume), new("Læsninger", Format.Number(disk.Reads)),
+                new("Gns. latens", $"{Format.Number(disk.AverageReadMs!.Value, 1)} ms"),
+                new("Læse-IOPS", Format.Number(disk.ReadIops ?? 0, 1)), new("Læst", $"{Format.Number(disk.ReadMbPerSecond ?? 0, 1)} MB/s"),
+                new("Langsomste filer", string.Join("; ", slowest)), new("Interval", $"{Format.Number(seconds / 60)} min"),
+            ]
+            :
+            [
+                new("Drev", disk.Volume), new("Skrivninger", Format.Number(disk.Writes)),
+                new("Gns. latens", $"{Format.Number(disk.AverageWriteMs!.Value, 1)} ms"),
+                new("Skrive-IOPS", Format.Number(disk.WriteIops ?? 0, 1)), new("Skrevet", $"{Format.Number(disk.WriteMbPerSecond ?? 0, 1)} MB/s"),
+                new("Langsomste filer", string.Join("; ", slowest)), new("Interval", $"{Format.Number(seconds / 60)} min"),
+            ];
+    }
 }
 
 /// <summary>
-/// Slow writes to transaction log files.
+/// Slow writes to the transaction log files on a drive (per drive, like <see cref="DataFileReadLatencyRule"/>).
 /// </summary>
 public sealed class LogFileWriteLatencyRule : Rule
 {
     public const int MinWrites = 1000;
 
     public override string Id => "SQLI-IO-002";
-    public override string Title => "Høj skrivelatens på logfiler";
+    public override string Title => "Høj skrivelatens på drev med logfiler";
     public override IReadOnlyCollection<Capability> RequiredCapabilities => [Capability.DynamicManagementViews];
 
     public override RuleEvaluation Evaluate(RuleContext context)
     {
         ArgumentNullException.ThrowIfNull(context);
         var delta = FileIo.Delta(context);
+        var seconds = (delta.To - delta.From).TotalSeconds;
         return Result(delta.Files
-            .Where(f => f.FileType == "LOG" && f.Writes >= MinWrites && f.AverageWriteLatencyMs >= 5)
+            .Where(f => f.FileType == "LOG")
-            .Select(f => CreateFinding(
+            .GroupBy(DiskVolumes.Of, StringComparer.OrdinalIgnoreCase)
-                f.AverageWriteLatencyMs >= 15 ? Severity.High : Severity.Medium,
+            .Select(g => (Files: g.ToList(), Disk: DiskActivity.ByVolume(g, seconds)[0]))
-                $"{f.DatabaseName}: {Format.Number(f.AverageWriteLatencyMs!.Value, 1)} ms i gennemsnit pr. logskrivning",
+            .Where(d => d.Disk.Writes >= MinWrites && d.Disk.AverageWriteMs >= 5)
+            .Select(d => CreateFinding(
+                d.Disk.AverageWriteMs >= 15 ? Severity.High : Severity.Medium,
+                $"{d.Disk.Volume} (logfiler): {Format.Number(d.Disk.AverageWriteMs!.Value, 1)} ms i gennemsnit pr. logskrivning",
                 "Hver commit venter på, at loggen er skrevet. Logskrivninger bør tage 1-2 ms; over 5 ms gør alle skrivende "
-                + "transaktioner mærkbart langsommere.",
+                + "transaktioner mærkbart langsommere, fx når brugerne bogfører eller gemmer.",
-                "Placér logfilen på storage med lav skrivelatens og write cache med batteribackup, adskilt fra datafilerne. "
+                "Placér logfilerne på storage med lav skrivelatens og write cache med batteribackup, adskilt fra datafilerne. "
-                + "Tjek, om andre filer eller VM'er deler samme volumen.",
+                + "Tjek, om andre filer eller VM'er deler samme drev, og om skrive-MB/s nærmer sig det, drevet kan levere.",
-                [new Evidence("Fil", f.PhysicalName), new Evidence("Skrivninger", Format.Number(f.Writes)),
+                DataFileReadLatencyRule.Evidence(d.Disk, d.Files, read: false, seconds),
-                 new Evidence("Gns. latens", $"{Format.Number(f.AverageWriteLatencyMs!.Value, 1)} ms")],
+                subject: $"volume: {d.Disk.Volume} log",
-                subject: $"file: {f.DatabaseName}/{f.FileId}",
                 references: Docs.Learn("sys.dm_io_virtual_file_stats", "relational-databases/system-dynamic-management-views/sys-dm-io-virtual-file-stats-transact-sql"))));
     }
 }

src/SQLInsight.Web/Components/Pages/Analysis.razor

@@ -115,6 +115,11 @@
     }
 </section>
 
+<section class="card">
+    <div class="card-head"><h2>Diskhastighed pr. drev</h2></div>
+    <DiskTable Disks="_analysis.Disks" ShowNormal="true" Empty="Ingen målinger pr. drev i tidsrummet (indsamles fra version 1.0.5)." />
+</section>
+
 <section class="card">
     <div class="card-head"><h2>I/O-latens pr. fil</h2></div>
     @if (_analysis.Files.Count == 0)

src/SQLInsight.Web/Components/Pages/Instance.razor

@@ -75,6 +75,21 @@ else
 }
 </section>
 
+<section class="card">
+<div class="card-head"><h2>Diskhastighed pr. drev, seneste 24 timer</h2></div>
+<DiskTable Disks="_disks" Empty="Endnu ingen målinger pr. drev (kræver to målinger efter opgradering til 1.0.5)." />
+@if (_diskSeries.Count > 0)
+{
+    <div class="grid2">
+        @foreach (var s in _diskSeries.Take(6))
+        {
+            <div class="panel"><Sparkline Points="s.MbPerSecond" Label="@($"{s.Volume} MB/s")" Decimals="1" /></div>
+            <div class="panel"><Sparkline Points="s.LatencyMs" Label="@($"{s.Volume} gns. latens (ms)")" Decimals="1" /></div>
+        }
+    </div>
+}
+</section>
+
 <section class="card">
 <div class="card-head"><h2>I/O-latens pr. fil, seneste 24 timer</h2></div>
 @if (_files.Count == 0)
@@ -223,6 +238,8 @@ else
     private IReadOnlyList<MetricPoint> _cpuSql = [], _cpuOther = [], _batches = [], _ple = [];
     private IReadOnlyList<WaitTotal> _waits = [];
     private IReadOnlyList<FileLatency> _files = [];
+    private IReadOnlyList<SQLInsight.Reports.DiskComparison> _disks = [];
+    private IReadOnlyList<DiskSeries> _diskSeries = [];
     private IReadOnlyList<StoredBlocking> _blocking = [];
     private IReadOnlyList<StoredDeadlock> _deadlocks = [];
 
@@ -247,6 +264,8 @@ else
         _ple = await Repository.GetMetricAsync(id, Metrics.PageLifeExpectancy, day);
         _waits = await Repository.GetTopWaitsAsync(id, day, 12);
         _files = await Repository.GetFileLatencyAsync(id, day);
+        _disks = (await Repository.GetDiskActivityAsync(id, day, DateTimeOffset.UtcNow)).Select(d => new SQLInsight.Reports.DiskComparison(d, null)).ToList();
+        _diskSeries = await Repository.GetDiskSeriesAsync(id, day);
         _blocking = await Repository.GetBlockingAsync(id, day);
         _deadlocks = await Repository.GetDeadlocksAsync(id, DateTimeOffset.UtcNow.AddDays(-7));
     }

src/SQLInsight.Web/Components/Shared/DiskTable.razor

@@ -0,0 +1,48 @@
+@* Disk speed per drive: IOPS, MB/s and average latency, optionally against the normal for the same hours. *@
+@if (Disks.Count == 0)
+{
+    <p class="muted">@Empty</p>
+}
+else
+{
+    <table>
+        <thead>
+            <tr>
+                <th>Drev</th><th class="num">Filer</th><th class="num">Læs IOPS</th><th class="num">Skriv IOPS</th>
+                <th class="num">Læs MB/s</th><th class="num">Skriv MB/s</th><th class="num">Gns. læs</th><th class="num">Gns. skriv</th>
+            </tr>
+        </thead>
+        <tbody>
+            @foreach (var d in Disks)
+            {
+                var w = d.Window;
+                <tr>
+                    <td class="mono">@w.Volume</td>
+                    <td class="num">@Files(w)</td>
+                    <td class="num">@Display.Number(w.ReadIops ?? 0, 1)</td>
+                    <td class="num">@Display.Number(w.WriteIops ?? 0, 1)</td>
+                    <td class="num">@Display.Number(w.ReadMbPerSecond ?? 0, 1)</td>
+                    <td class="num">@Display.Number(w.WriteMbPerSecond ?? 0, 1)</td>
+                    <td class="num @(w.AverageReadMs >= 20 || Worse(w.AverageReadMs, d.Normal?.AverageReadMs) ? "bad" : "")">@Ms(w.AverageReadMs)@Normal(d.Normal?.AverageReadMs)</td>
+                    <td class="num @(w.AverageWriteMs >= (w.DataFiles == 0 && w.LogFiles > 0 ? 5 : 20) || Worse(w.AverageWriteMs, d.Normal?.AverageWriteMs) ? "bad" : "")">@Ms(w.AverageWriteMs)@Normal(d.Normal?.AverageWriteMs)</td>
+                </tr>
+            }
+        </tbody>
+    </table>
+    <p class="muted">Latens er gennemsnitstiden pr. læsning/skrivning set fra SQL Server (sys.dm_io_virtual_file_stats). Datafiler bør ligge under 10-20 ms, logfiler under 5 ms.@(ShowNormal ? " I parentes: det normale for samme klokkeslæt de foregående uger." : "")</p>
+}
+
+@code {
+    [Parameter, EditorRequired] public IReadOnlyList<SQLInsight.Reports.DiskComparison> Disks { get; set; } = [];
+    [Parameter] public string Empty { get; set; } = "Ingen målinger pr. drev endnu.";
+    [Parameter] public bool ShowNormal { get; set; }
+
+    private static string Ms(double? value) => value is { } v ? $"{Display.Number(v, 1)} ms" : "–";
+
+    private string Normal(double? value) => ShowNormal && value is { } v ? $" ({Display.Number(v, 1)})" : "";
+
+    private static string Files(SQLInsight.Core.Data.DiskActivity d) =>
+        d.DataFiles + d.LogFiles == 0 ? "–" : $"{d.DataFiles} data · {d.LogFiles} log";
+
+    private static bool Worse(double? now, double? normal) => now is { } n && normal is > 0 and var m && n >= m * 2 && n - m >= 2;
+}

tests/SQLInsight.Core.Tests/DiskTests.cs

@@ -0,0 +1,64 @@
+using SQLInsight.Core.Data;
+
+namespace SQLInsight.Core.Tests;
+
+public class DiskTests
+{
+    [Theory]
+    [InlineData(@"D:\SQLData\Sales.mdf", @"D:\")]
+    [InlineData(@"l:\Logs\Sales_log.ldf", @"L:\")]
+    [InlineData(@"\\nas01\sql\Sales.mdf", @"\\nas01\sql\")]
+    [InlineData("/var/opt/mssql/data/master.mdf", "/")]
+    public void Drive_is_derived_from_the_file_path(string physicalName, string volume) =>
+        Assert.Equal(volume, DiskVolumes.FromPhysicalName(physicalName));
+
+    [Fact]
+    public void Reported_volume_wins_over_the_path()
+    {
+        var mountPoint = File("Sales", 1, "ROWS", @"D:\Mounts\Data1\Sales.mdf") with { Volume = @"D:\Mounts\Data1\" };
+
+        Assert.Equal(@"D:\Mounts\Data1\", DiskVolumes.Of(mountPoint));
+        Assert.Equal(@"D:\", DiskVolumes.Of(mountPoint with { Volume = null }));
+    }
+
+    [Fact]
+    public void Files_are_summed_per_drive_with_rates_and_weighted_latency()
+    {
+        var files = new[]
+        {
+            File("Sales", 1, "ROWS", @"D:\Sales.mdf", reads: 3000, bytesRead: 300 * 1048576L, readStall: 30_000),
+            File("Stock", 1, "ROWS", @"D:\Stock.mdf", reads: 1000, bytesRead: 0, readStall: 50_000),
+            File("Sales", 2, "LOG", @"L:\Sales_log.ldf", writes: 6000, bytesWritten: 60 * 1048576L, writeStall: 12_000),
+        };
+
+        var disks = DiskActivity.ByVolume(files, seconds: 300);
+
+        Assert.Equal([@"D:\", @"L:\"], disks.Select(d => d.Volume));
+        var data = disks[0];
+        Assert.Equal(2, data.DataFiles);
+        Assert.Equal(0, data.LogFiles);
+        Assert.Equal(4000 / 300.0, data.ReadIops);
+        Assert.Equal(1.0, data.ReadMbPerSecond);
+        Assert.Equal(20, data.AverageReadMs); // 80 s over 4000 reads, not the average of 10 and 50 ms
+        Assert.Null(data.AverageWriteMs);
+        var log = disks[1];
+        Assert.Equal(20, log.WriteIops);
+        Assert.Equal(0.2, log.WriteMbPerSecond!.Value, 6);
+        Assert.Equal(2, log.AverageWriteMs);
+    }
+
+    private static FileIoStat File(string db, int id, string type, string path, long reads = 0, long bytesRead = 0, long readStall = 0,
+        long writes = 0, long bytesWritten = 0, long writeStall = 0) => new()
+    {
+        DatabaseName = db,
+        FileId = id,
+        FileType = type,
+        PhysicalName = path,
+        Reads = reads,
+        BytesRead = bytesRead,
+        ReadStallMs = readStall,
+        Writes = writes,
+        BytesWritten = bytesWritten,
+        WriteStallMs = writeStall,
+    };
+}

tests/SQLInsight.IntegrationTests/CollectorTests.cs

@@ -103,6 +103,8 @@ public class CollectorTests(SqlServerFixture sql)
         var pc2 = await session.CollectAsync(new PerformanceCounterCollector(), pc1);
 
         Assert.Contains(io1.Snapshot.Files, f => f.DatabaseName == "master" && f.FileType == "LOG");
+        // SQL Server 2022 has sys.dm_os_volume_stats: every file knows its drive (a mount point on Linux).
+        Assert.All(io1.Snapshot.Files, f => Assert.False(string.IsNullOrWhiteSpace(f.Volume)));
         Assert.NotNull(io2.Delta);
         Assert.NotNull(pc1.Snapshot.PageLifeExpectancySeconds);
         Assert.NotNull(pc1.Snapshot.MemoryGrantsPending);

tests/SQLInsight.IntegrationTests/TimeWindowAnalysisTests.cs

@@ -146,6 +146,7 @@ public class TimeWindowAnalysisTests(SqlServerFixture sql) : IAsyncLifetime
         var html = await client.GetStringAsync($"/instanser/{name}/analyse?{Window(from, to)}");
         Assert.Contains("SELECT * FROM SALESLINE", html, StringComparison.Ordinal);
         Assert.Contains("LCK_M_X", html, StringComparison.Ordinal);
+        Assert.Contains("Diskhastighed pr. drev", html, StringComparison.Ordinal);
         Assert.Contains("class=\"unusual\"", html, StringComparison.Ordinal);
         Assert.Contains("value=\"" + TimeWindow.ToInput(from, Copenhagen) + "\"", html, StringComparison.Ordinal);
 
@@ -163,6 +164,51 @@ public class TimeWindowAnalysisTests(SqlServerFixture sql) : IAsyncLifetime
         Assert.StartsWith("%PDF", System.Text.Encoding.ASCII.GetString(await pdf.Content.ReadAsByteArrayAsync())[..4], StringComparison.Ordinal);
     }
 
+    [Fact]
+    public async Task Disk_speed_is_summed_per_drive_and_kept_hourly()
+    {
+        var to = FloorHour(DateTimeOffset.UtcNow).AddHours(-1);
+        var from = to.AddHours(-1);
+        for (var at = from.AddMinutes(5); at <= to; at = at.AddMinutes(5))
+        {
+            await _repository.SaveCollectedAsync(_instanceId, "file-io", new CumulativeSample<FileIoSnapshot, FileIoDelta>(
+                new FileIoSnapshot { CapturedAt = at, SqlServerStartTime = DateTime.UtcNow.AddDays(-1), Files = [] },
+                new FileIoDelta
+                {
+                    From = at.AddMinutes(-5),
+                    To = at,
+                    Files =
+                    [
+                        IoFile("AX30", 1, "ROWS", @"D:\AX30.mdf", reads: 3000, readStall: 90_000, bytesRead: 300 * 1048576L),
+                        IoFile("AX30", 2, "LOG", @"L:\AX30_log.ldf", writes: 3000, writeStall: 3_000, bytesWritten: 30 * 1048576L),
+                    ],
+                }));
+        }
+
+        await _repository.RunMaintenanceAsync(new RetentionOptions(), DateTimeOffset.UtcNow);
+        var raw = await _repository.GetDiskActivityAsync(_instanceId, from, to);
+        var hourly = await _repository.GetDiskActivityHourlyAsync(_instanceId, from, to);
+        var analysis = await TimeWindowAnalysis.LoadAsync(_repository, (await _repository.GetInstanceAsync(@"AX01\AX30"))!, from, to, DateTimeOffset.UtcNow);
+
+        var data = raw.Single(d => d.Volume == @"D:\");
+        Assert.Equal(1, data.DataFiles);
+        Assert.Equal(30, data.AverageReadMs);
+        Assert.Equal(10, data.ReadIops);       // 3000 reads per 300 s
+        Assert.Equal(1, data.ReadMbPerSecond); // 300 MB per 300 s
+        Assert.Equal(1, raw.Single(d => d.Volume == @"L:\").AverageWriteMs);
+        // The sample on the hour belongs to the next hour (as for waits): 11 samples of 300 s in this one.
+        Assert.Equal(11 * 300, hourly.Single(d => d.Volume == @"D:\").Seconds);
+        Assert.True(analysis.Disks.Single(d => d.Window.Volume == @"D:\").IsSlow);
+        Assert.False(analysis.Disks.Single(d => d.Window.Volume == @"L:\").IsUnusual);
+    }
+
+    private static FileIoStat IoFile(string db, int id, string type, string path, long reads = 0, long readStall = 0, long bytesRead = 0,
+        long writes = 0, long writeStall = 0, long bytesWritten = 0) => new()
+    {
+        DatabaseName = db, FileId = id, FileType = type, PhysicalName = path, Reads = reads, ReadStallMs = readStall, BytesRead = bytesRead,
+        Writes = writes, WriteStallMs = writeStall, BytesWritten = bytesWritten,
+    };
+
     /// <summary>A busy hour: high CPU, lock waits and one heavy statement, against quiet same hours four weeks back.</summary>
     private async Task SeedWindowAsync(DateTimeOffset from, DateTimeOffset to)
     {

tests/SQLInsight.Rules.Tests/PerformanceRuleTests.cs

@@ -96,6 +96,22 @@ public class PerformanceRuleTests
         }
     }
 
+    [Fact]
+    public void Slow_data_files_on_one_drive_give_one_finding_for_the_drive()
+    {
+        var sales = File("ROWS", reads: 3000, readStallMs: 90_000);            // 30 ms
+        var stock = File("ROWS", reads: 2000, readStallMs: 40_000) with { DatabaseName = "Stock", FileId = 1, PhysicalName = @"D:\Stock.mdf" };
+        var fast = File("ROWS", reads: 5000, readStallMs: 5_000) with { DatabaseName = "Fast", PhysicalName = @"E:\Fast.mdf" };
+
+        var result = Run(new DataFileReadLatencyRule(), With(Io(sales, stock, fast)));
+
+        var finding = Assert.Single(result.Findings);
+        Assert.Equal(@"volume: D:\ data", finding.Subject);
+        Assert.Contains(@"D:\ (datafiler): 26,0 ms", finding.Title, StringComparison.Ordinal); // 130 s over 5000 reads
+        Assert.Contains(finding.Evidence, e => e.Name == "Langsomste filer" && e.Value.StartsWith("Sales 30,0 ms", StringComparison.Ordinal));
+        Assert.Contains(finding.Evidence, e => e.Name == "Læse-IOPS");
+    }
+
     private static CpuUtilization Cpu(int sql, int idle, int minutes = 15, string platform = "Windows") => new()
     {
         CapturedAt = Now,