I had a client ask me to create a mailbox creation script that would create new mailboxes on the smallest DB in the US.
After doing a bit of research and running into some issue with the Get-MailboxDatabase cmdlet returining 0 for the DatabaseSize property I came up with the following script.
# This script will return the smallest mailbox database, which can be useful when creating new mailboxes or re-distributing based on size
# Created by Jason Sherry (izzy@izzy.org) 3/25/2012
# Last Updated: 6/16/2012
# Source: http://izzy.org/scripts/Exchange/Admin/Get-SmallestDB.ps1
# Partial code source: http://powershell.com/cs/media/p/3981.aspx
$MBXDbs = Get-MailboxDatabase | Where-Object {$_.Identity -notlike "TCN-EU-*"} # This will exclude any DB that started with "TCN-EU-"
# Loop through each of the MBXDbs
ForEach ($MBXDB in $MBXDbs) {
# Get current mailboxes sizes by summing the size of all mailboxes and "Deleted Items" in the database
$TotalItemSize = Get-MailboxStatistics -Database $MBXDB | %{$_.TotalItemSize.Value.ToMB()} | Measure-Object -sum
$TotalDeletedItemSize = Get-MailboxStatistics -Database $MBXDB.DistinguishedName | %{$_.TotalDeletedItemSize.Value.ToMB()} | Measure-Object -sum
#Get-MailboxDatabase and the DatabaseSize property was not used since it does not return a value in some environments as of 2010 SP2
$TotalDBSize = $TotalItemSize.Sum + $TotalDeletedItemSize.Sum
# Compare the sizes to find the smallest DB
If (($TotalDBSize -lt $SmallestDBsize) -or ($SmallestDBsize -eq $null))
{
$SmallestDBsize = $TotalDBSize
$SmallestDB = $MBXDB
}
}
Write-host "Smallest DB: " $SmallestDB
Jason (Izzy) Sherry's Blog 