A more constructive answer : http://technet.microsoft.com/en-us/library/cc179067(office.14).aspx
"Offline folder (.ost file) recommendations: When you deploy Cached Exchange Mode for Outlook, be aware that users' local .ost files can increase 50 percent to 80 percent over the size of the mailbox reported in Exchange Server. The format Outlook uses to store data locally for Cached Exchange Mode is less space-efficient than the server data file format. This results in the use of more disk space when mailboxes are downloaded to provide a local copy for Cached Exchange Mode. When Cached Exchange Mode first creates a local copy of a user's mailbox, the user's current .ost file, if one exists, is updated. If users currently have non-Unicode ANSI-formatted .ost files, we recommend that you upgrade their .ost files to Unicode. Non-Unicode (ANSI) Outlook files have a limit of 2 gigabytes (GB) of data storage. The maximum size for Unicode .ost files is configurable, with the default being 50 GB of data storage." You may also try to do a compress on the OST file to see if you reclaim the space. I am doing my 2010 upgrade sometime next week. My OST is about 6 gig right now, so I am curious as well. Greg -----Original Message----- From: Bill Egan [mailto:william.e...@gmail.com] Sent: Monday, May 03, 2010 11:40 PM To: MS-Exchange Admin Issues Subject: OST Size - and Outlook 2010 Installed Office 2010 today after a clean uninstall of O2k7. After a long conversion process and a still incomplete index, I looked at the size of my OST. Its now 6.3gig. If I do a folder size on my mailbox, the server data shows 1.2G and the local data shows 2.3g. Both 1.2 and 2.3 to 6.3 are big discrepancies. does this strike anyone else as odd or wrong? thanks, began
