The most difficult duty for Exchange Administrators is determining the available space in the environment for Mailbox Databases to separate and manage Mailboxes appropriately.
The following commands will assist the Mailbox Database and other databases on the server in determining the amount of available free space.
Get-MailboxDatabase -ID “EX01-DB01” -Status | Select-Object Server,Name,Available
If you want to find out the names of all the Mailbox Databases on the server, use the following command.
Select-Object ServerName,Name,Available | Get-MailboxDatabase -Status