EV will increase OST size ?

[John_Tseung]

Archive to EV can reduce the OST space?

a user using EV and the OST size is 19GB and corrupt.

Rebuild OST without EV the OST actual size is 11.4GB only.

Please help. Thanks.

[AndrewB]

if you're removing the email from the mailbox or using shortcutting then yes, archiving naturally will decrease the mailbox size which, in turn, should result in a smaller OST file.

when you say you rebuilt OST without EV, what does that mean?

what version of Outlook on the client, Exchange, and EV server and client are you using?

[Chris_Warren]

My concern is regarding the OST being 19 GB and corrupt. Is it possible that a corrupt OST could cause it to not be able to reclaim unused space?  Perhaps running a repair on the OST could have also fixed it?

As Andrew referenced, depending on your shortcut creation rules, EV will normally decrease the total size of the Mailbox.  However, some factors to take into consideration:

- Entire message content.  Setting shortcut creation to this means that the only space reclaimed will be from the removal of attachments.

- Small items.  In some cases, where an item is very small, less than 4 KB, the shortcut may actually be slightly larger due to the additional mapi properties and EV specific content.

As a general rule I try to keep any PST or OST under 14 GB for stability reasons.

Hope this helps.

[JesusWept3 · Accepted solution]

I could be wrong, but the structure of an OST isn't all that different from a PST right?
If you have a pst thats 500mb and delete all the items, the PST file remains at 500MB

But if you're editing items that are say 500MB in size down to maybe 50MB of shortcuts, the OST is not going to shrink down to 50MB, it will remain at 500MB no?
So is it just possible that you had 8GB of white space that was no longer needed when you rebuilt the cache?

[Chris_Warren]

I believe you are right JW2, the following article describes compacting the OST, which appears to be a manual process:

http://www.ostfile.com/compact-ost-file.html

Hope this helps.

[Michael_Bilsbor]

I recently came across this registry key and wondered if it might be having an impact.  We found very recently it causes big delays opening items in VV if it's set but it might at least be interesting to set it to see if it impacts the size of the OST?

http://support.microsoft.com/kb/2022995

[AndrewB]

the comments about the OST file not reducing in size on its own is not completely accurate. Outlook has a built-in mechanism to do just that but it's not going to work of the OST file is corrupt or if Outlook is closed most of the time.

[AndrewB]

john, have you sorted this out yet?