tests/Test-SqlServerMemory.ps1

function Test-SqlServerMemory {
    [CmdletBinding()]
    param (
        [parameter()][string] $TestName = "Test-SqlServerMemory",
        [parameter()][string] $TestGroup = "database",
        [parameter()][string] $Description = "Validate maximum memory allocation of SQL instance",
        [parameter()][hashtable] $ScriptParams,
        [parameter()][int] $MaxMemAllocation = 0.8
    )
    try {
        [System.Collections.Generic.List[PSObject]]$tempdata = @() # for detailed test output to return if needed
        $stat = "PASS"
        $msg  = "No issues found"
        $unlimited = 2147483647
        # get total memory allocated to SQL Server in MB
        if ($ScriptParams.Credential) {
            $cmax = (Get-DbaMaxMemory -SqlInstance $ScriptParams.SqlInstance -EnableException -ErrorAction SilentlyContinue -SqlCredential $ScriptParams.Credential).MaxValue
        } else {
            $cmax = (Get-DbaMaxMemory -SqlInstance $ScriptParams.SqlInstance -EnableException -ErrorAction SilentlyContinue).MaxValue
        }
        Write-Verbose "current sql limit = $cmax MB"
        # get total physical memory of host in MB
        if ($ScriptParams.Credential) {
            $tmem = (Get-DbaComputerSystem -ComputerName $ScriptParams.SqlInstance -EnableException -ErrorAction SilentlyContinue -Credential $ScriptParams.Credential).TotalPhysicalMemory.Megabyte
        } else {
            $tmem = (Get-DbaComputerSystem -ComputerName $ScriptParams.SqlInstance -EnableException -ErrorAction SilentlyContinue).TotalPhysicalMemory.Megabyte
        }
        Write-Verbose "total physical memory = $tmem MB"
        $target = $tmem * $MaxMemAllocation
        Write-Verbose "target memory = $target"
        $target = [math]::Round($target, 0)
        Write-Verbose "target memory = $target (rounded)"
        if ($cmax -eq $unlimited) {
            $stat = 'FAIL'
            $msg  = "Current SQL Server max memory is unlimited. Should be limited to 80 percent of total physical memory."
        } else {
            if ($cmax -gt $tmem) {
                $stat = "FAIL"
                $msg  = "Current limit $($cmax) MB is greater than physical $($tmem) MB - possibly due to virtual dynamic memory"
            } elseif ($cmax -gt $target) {
                $stat = "FAIL"
                $msg  = "Current limit $($cmax) MB is greater than 80 percent physical $($tmem) MB or $($target) MB"
            }
        }
        if ($Remediate -eq $True) {
            if ($ScriptParams.Credential) {
                Set-DbaMaxMemory -SqlInstance $ScriptParams.SqlInstance -Max $target -EnableException -ErrorAction SilentlyContinue -SqlCredential $ScriptParams.Credential
            } else {
                Set-DbaMaxMemory -SqlInstance $ScriptParams.SqlInstance -Max $target -EnableException -ErrorAction SilentlyContinue
            }
            $stat = 'REMEDIATED'
            $msg  = "SQL Server max memory is now set to $target MB"
        }
    }
    catch {
        $stat = 'ERROR'
        $msg = $_.Exception.Message -join ';'
    }
    finally {
        Write-Output $([pscustomobject]@{
            TestName    = $TestName
            TestGroup   = $TestGroup
            TestData    = $tempdata
            Description = $Description
            Status      = $stat 
            Message     = $msg
            Credential  = $(if($ScriptParams.Credential){$($ScriptParams.Credential).UserName} else { $env:USERNAME })
        })
    }
}