functions/Get-DbaIoLatency.ps1
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function Get-DbaIoLatency { <# .SYNOPSIS Displays IO subsystem latency statistics from sys.dm_io_virtual_file_stats. Works on SQL Server 2005 and above. .DESCRIPTION This command is based off of Paul Randal's post "Advanced SQL Server performance tuning" Returns both raw and aggregate information Reference: https://www.sqlskills.com/blogs/paul/how-to-examine-io-subsystem-latencies-from-within-sql-server/ https://www.sqlskills.com/blogs/paul/capturing-io-latencies-period-time/ .PARAMETER SqlInstance The SQL Server instance. Server version must be SQL Server version 2008 or higher. .PARAMETER SqlCredential Login to the target instance using alternative credentials. Windows and SQL Authentication supported. Accepts credential objects (Get-Credential) .PARAMETER EnableException By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message. This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting. Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch. .NOTES Tags: IOLatency Author: Patrick Flynn (@sqllensman) Website: https://dbatools.io Copyright: (c) 2018 by dbatools, licensed under MIT License: MIT https://opensource.org/licenses/MIT .LINK https://dbatools.io/Get-DbaIoLatency .EXAMPLE PS C:\> Get-DbaIoLatency -SqlInstance sql2008, sqlserver2012 Get IO subsystem latency statistics for servers sql2008 and sqlserver2012. .EXAMPLE PS C:\> $output = Get-DbaIoLatency -SqlInstance sql2008 | Select-Object * | ConvertTo-DbaDataTable Collects all IO subsystem latency statistics on server sql2008 into a Data Table. .EXAMPLE PS C:\> 'sql2008','sqlserver2012' | Get-DbaIoLatency Get IO subsystem latency statistics for servers sql2008 and sqlserver2012 via pipline .EXAMPLE PS C:\> $cred = Get-Credential sqladmin PS C:\> Get-DbaIoLatency -SqlInstance sql2008 -SqlCredential $cred Connects using sqladmin credential and returns IO subsystem latency statistics from sql2008 #> [CmdletBinding()] Param ( [parameter(Mandatory, ValueFromPipeline)] [Alias("ServerInstance", "SqlServer", "SqlServers")] [DbaInstance[]]$SqlInstance, [PSCredential]$SqlCredential, [Alias('Silent')] [switch]$EnableException ) BEGIN { $sql = "SELECT [vfs].[database_id], DB_NAME ([vfs].[database_id]) AS [DatabaseName], [vfs].[file_id], [mf].[physical_name], [num_of_reads], [io_stall_read_ms], [num_of_writes], [io_stall_write_ms], [io_stall], [num_of_bytes_read], [num_of_bytes_written], [sample_ms], [size_on_disk_bytes], [file_handle], [ReadLatency] = CASE WHEN [num_of_reads] = 0 THEN 0 ELSE ([io_stall_read_ms] / [num_of_reads]) END, [WriteLatency] = CASE WHEN [num_of_writes] = 0 THEN 0 ELSE ([io_stall_write_ms] / [num_of_writes]) END, [Latency] = CASE WHEN ([num_of_reads] = 0 AND [num_of_writes] = 0) THEN 0 ELSE ([io_stall] / ([num_of_reads] + [num_of_writes])) END, [AvgBPerRead] = CASE WHEN [num_of_reads] = 0 THEN 0 ELSE ([num_of_bytes_read] / [num_of_reads]) END, [AvgBPerWrite] = CASE WHEN [num_of_writes] = 0 THEN 0 ELSE ([num_of_bytes_written] / [num_of_writes]) END, [AvgBPerTransfer] = CASE WHEN ([num_of_reads] = 0 AND [num_of_writes] = 0) THEN 0 ELSE (([num_of_bytes_read] + [num_of_bytes_written]) / ([num_of_reads] + [num_of_writes])) END FROM sys.dm_io_virtual_file_stats (NULL,NULL) AS [vfs] INNER JOIN sys.master_files AS [mf] ON [vfs].[database_id] = [mf].[database_id] AND [vfs].[file_id] = [mf].[file_id];" Write-Message -Level Debug -Message $sql $excludeColumns = 'FileHandle', 'ReadLatency', 'WriteLatency', 'Latency', 'AvgBPerRead', 'AvgBPerWrite', 'AvgBPerTransfer' } process { if (Test-FunctionInterrupt) { return } foreach ($instance in $SqlInstance) { if (Test-FunctionInterrupt) { return } Write-Message -Level Verbose -Message "Connecting to $instance" try { $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $SqlCredential -MinimumVersion 9 } catch { Stop-Function -Message "Error occurred while establishing connection to $instance" -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue } Write-Message -Level Verbose -Message "Connected to $instance" foreach ($row in $server.Query($sql)) { [PSCustomObject]@{ ComputerName = $server.NetName InstanceName = $server.ServiceName SqlInstance = $server.DomainInstanceName DatabaseId = $row.database_id DatabaseName = $row.DatabaseName FileId = $row.file_id PhysicalName = $row.physical_name NumberOfReads = $row.num_of_reads IoStallRead = $row.io_stall_read_ms NumberOfwrites = $row.num_of_writes IoStallWrite = $row.io_stall_write_ms IoStall = $row.io_stall NumberOfBytesRead = $row.num_of_bytes_read NumberOfBytesWritten = $row.num_of_bytes_written SampleMilliseconds = $row.sample_ms SizeOnDiskBytes = $row.num_of_bytes_written FileHandle = $row.file_handle ReadLatency = $row.ReadLatency WriteLatency = $row.WriteLatency Latency = $row.Latency AvgBPerRead = $row.AvgBPerRead AvgBPerWrite = $row.AvgBPerWrite AvgBPerTransfer = $row.AvgBPerTransfer } | Select-DefaultView -ExcludeProperty $excludeColumns } } } } |