Quickie: Total Deleted Item Size Per DB

We are considering doubling our Deleted Item Retention period from 14 days to 28 days. I am guesstimating that this means doubling each mailboxes 'Total Deleted Items Size".  Here's the script I used to capture what the current size is for each DB.

Get-MailboxDatabase | sort Name | %{write-host $_.name; $_ | Get-MailboxStatistics | select database,@{Name="DeletedItemSize";Expression={$_.totalDeletedItemSize.value.tomb()}} |  measure-object -property DeletedItemSize -sum } | %{($_.sum).tostring() + "MB"}

This dumps to the screen a report that looks like:

HR-DB01
10875MB
HR-DB02
8597MB
HR-DB03
7535MB


I take this to mean that DB1 should grow by ~10GB in size when I double the DeletedItemRetention period to 4 weeks.

Revision 2: Returns an Object..

Get-MailboxDatabase | select Name,@{Name="DIR";Expression={ %{ $_ | Get-MailboxStatistics | select database,@{Name="DeletedItemSize";Expression={$_.totalDeletedItemSize.value.tomb()}} |  measure-object -property DeletedItemSize -sum } | %{$_.sum}}} | sort DIR

Name                                                                 DIR
----                                                                     ---
SALES-DB03                                                    10944
SALES-DB01                                                    10990
SALES-DB02                                                    11008


Revision 3: Add Physical DB size.

Get-MailboxDatabase -status | select Name,@{Name="DIR";Expression={ %{ $_ | Get-MailboxStatistics | select database,@{Name="DeletedItemSize";Expression={$_.totalDeletedItemSize.value.tomb()}} |  measure-object -property DeletedItemSize -sum } | %{$_.sum}}},@{Name="PhysicalDBSize";Expression={$_.databaseSize.tomb()}}

Now, I can filter the results to show only those that might exceed the 1TB mount points I have each DB. If for example I feed all of the above into a variable, $AllDBS. Then I can filter, when the results are going to be greater than, or close to our 1TB mount points.

For DBs that would be larger than 600MB in size.
$AllDBS  | ?{(($_.dir*2) + $_.physicaldbsize) -ge 600000}

Name                                                                        DIR                          PhysicalDBSize
----                                                                        ---                          --------------
IT-DB02                                                                  15643                                  588553
IT-DB03                                                                  11989                                  604681
IT-DB05                                                                  12975                                  663946
IT-DB01                                                                  16987                                  661641