Calculating deleted-item cache size for a database LUN

Run the Windows Performance Monitor utility (also known as "Perfmon").

Right-click the graph and select Add Counters.

Result

The Add Counters dialog box is displayed.

In the Performance Object drop-down list, select the performance object MSExchangeIS Mailbox.

In the Select Counter From List option, select Total Size of Recoverable Items.

Select all databases in the instances list for the storage group you are measuring.

Click Add.

Result

PerfMon provides the total size of recoverable items (in the selected storage group) in kilobytes.

To calculate the deleted-item cache size as a percentage value for use in the LUN size Calculation formula, divide the total size of recoverable items (in kilobytes) by the total size of the database (in kilobytes).