functions/Get-DbaMaxMemory.ps1

#ValidationTags#Messaging,FlowControl,Pipeline,CodeStyle#
function Get-DbaMaxMemory {
<#
    .SYNOPSIS
        Gets the 'Max Server Memory' configuration setting and the memory of the server. Works on SQL Server 2000-2014.
         
    .DESCRIPTION
        This command retrieves the SQL Server 'Max Server Memory' configuration setting as well as the total physical installed on the server.
         
    .PARAMETER SqlInstance
        Allows you to specify a comma separated list of servers to query.
         
    .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: MaxMemory, Memory
        Author: Chrissy LeMaire (@cl), netnerds.net
        Website: https://dbatools.io
        Copyright: (c) 2018 by dbatools, licensed under MIT
        License: MIT https://opensource.org/licenses/MIT
         
    .LINK
        https://dbatools.io/Get-DbaMaxMemory
         
    .EXAMPLE
        Get-DbaMaxMemory -SqlInstance sqlcluster,sqlserver2012
         
        Get memory settings for all servers within the SQL Server Central Management Server "sqlcluster".
         
    .EXAMPLE
        Get-DbaMaxMemory -SqlInstance sqlcluster | Where-Object { $_.SqlMaxMB -gt $_.TotalMB }
         
        Find all servers in Server Central Management Server that have 'Max Server Memory' set to higher than the total memory of the server (think 2147483647)
         
#>

    [CmdletBinding()]
    param (
        [parameter(Position = 0, Mandatory, ValueFromPipeline)]
        [Alias("ServerInstance", "SqlServer", "SqlServers")]
        [DbaInstanceParameter[]]$SqlInstance,
        [PSCredential]$SqlCredential,
        [Alias('Silent')]
        [switch]$EnableException
    )

    process {
        foreach ($instance in $SqlInstance) {
            try {
                Write-Message -Level Verbose -Message "Connecting to $instance"
                $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $sqlcredential
            }
            catch {
                Stop-Function -Message "Failure" -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue
            }

            $totalMemory = $server.PhysicalMemory

            # Some servers under-report by 1MB.
            if (($totalMemory % 1024) -ne 0) {
                $totalMemory = $totalMemory + 1
            }

            [pscustomobject]@{
                ComputerName = $server.ComputerName
                InstanceName = $server.ServiceName
                SqlInstance  = $server.DomainInstanceName
                TotalMB      = [int]$totalMemory
                SqlMaxMB     = [int]$server.Configuration.MaxServerMemory.ConfigValue
            } | Select-DefaultView -ExcludeProperty Server
        }
    }
}