Exchange 2003 IS size - growing more than it should?

We upgraded from Exchange 5.5 to Exchange 2003 about 8 months ago.  At the time, our 5.5 IS was around 15GB.  When we checked the size in 2003, it was showing closer to 30GB.

8 months later, our IS is showing 60GB.  When adding up the mailboxes, it only comes to 20GB.

Can anyone point me in the right direction as to what is going on?  We have a single Exchange server, and are using two stores; one for regular employees and one for executives.  Each is roughly 30GB.  Why would the size of the IS grow so much when the mailboxes only total 20GB?
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SembeeConnect With a Mentor Commented:
You cannot add up the total of the mailboxes and expect it to match the size of the files.
There are many factors that can determine a difference.

- single instance storage
- deleted item retention
- white space in the database.

White space is logged every night in event ID 1221, where it is called free space.
SIS ratio and deleted item retention size can be found using perfmon.

edensandavantAuthor Commented:
Thanks Simon.  Happen to know offhand which Performance Object in perfmon I need to be looking at?
Deleted items is


Total Size of Recoverable Items - I think that one is in bytes, so divide by 104 to get kb etc.

SIS is Same counter set, Single Instance Ratio. However that one doesn't really tell you a great deal.

edensandavantAuthor Commented:
OK, I see it.  The Total Size of Recoverable Items is in KB, and it is 37GB, so it looks like that is where all the space is.

Thanks for your help Simon!

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