There are issues in monitoring Mailbox Store size when the Mailbox stores are located on NetAppFiler or some other SAN or Storage Units. SOE (Spotlight on Exchange) may show the Storage Group size 0 MB or -2.
SOE does not support NetAppFiler, SAN, or other network-attached Storage Devices. SOE cannot collect the size of Stores or the free disk size on the drives that Stores are on.
Refer to Microsoft's Article ID 839687 - "Microsoft support policy on the use of network-attached storage devices with Exchange Server 2003", for information on Microsoft's Support Policy: http://support.microsoft.com/kb/839687
WORKAROUND
Disable these counters if alarms are raised.
OR
Extract the attached zip file and run the EnableSan.reg file on the SOE system, which will enter in the following registry value under the path below:
"S A N M o d e " = d w o r d : 0 0 0 0 0 0 0 1
[ H K E Y _ L O C A L _ M A C H I N E \ S O F T W A R E \ Q u e s t S o f t w a r e \ S p o t l i g h t o n E x c h a n g e ]
NOTE: This is not guaranteed to work but has been successfully implemented for a number of customers.
STATUS
Waiting for fix in a future release of Spotlight on Exchange.