I'm having a really tough time with my exchange server this week. I started getting calls on Monday saying people could not connect to Exchange. When I checked the event logs I found the following relevant items under the Application log: Event 9646 Mapi session "/O=PATH/OU=PATH/cn=Recipients/cn=USERNAME" exceeded the maximum of 32 objects of type "session". Event 1022 Logon Failure on database "Back Office 1\HR" - Windows 2000 account DOMAIN\USERNAME; mailbox /O=PATH/OU=PATH/cn=Recipients/cn=USERNAME. Error: -1069 Event 9791 Cleanup of the DeliveredTo table for database 'Back Office 1\Marketing' was pre-empted because the database engine's version store was growing too large. 0 entries were purged. Event 623 Information Store (2928) Back Office 1: The version store for this instance (0) has reached its maximum size of 108Mb. It is likely that a long-running transaction is preventing cleanup of the version store and causing it to build up in size. Updates will be rejected until the long-running transaction has been completely committed or rolled back. Possible long-running transaction: SessionId: 0xBD334800 Session-context: 0x00000000 Session-context ThreadId: 0x00000158 Cleanup: 1 Clearly there is a database problem on the information store Back Office 1 and all of the users seeing the problem are in that store. I would greatly appreciate any help, this has become a major problem at this point. The only thing I could think to do is create a new Information Store and migrate everyone over to it but I can't be sure this is the best (and fastest) way to fix this.

623's usually indicates you have performance bottlenecks particularly with memory or IO bottlenecks. You can verify by looking at the log stalls in perfmon. When you have too much memory pressure, you can exhaust your version store memory faster than it can reclaim. I ran into this with an already bottlenecked server and an admin opening up a 100GB mailbox causing the version store memory to exchaust. You need to capture perfmon to see where the bottleneck is. Download the whitepaper below it will give you all the perf counters and their recommended thresholds. I would focus on logstalls, disk IO avg disk sec read\write latency, rpc latency. Troubleshooting Microsoft Exchange Server Performance http://www.microsoft.com/en-us/download/details.aspx?id=19125James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

623's usually indicates you have performance bottlenecks particularly with memory or IO bottlenecks. You can verify by looking at the log stalls in perfmon. When you have too much memory pressure, you can exhaust your version store memory faster than it can reclaim. I ran into this with an already bottlenecked server and an admin opening up a 100GB mailbox causing the version store memory to exchaust. You need to capture perfmon to see where the bottleneck is. Download the whitepaper below it will give you all the perf counters and their recommended thresholds. I would focus on logstalls, disk IO avg disk sec read\write latency, rpc latency. Troubleshooting Microsoft Exchange Server Performance http://www.microsoft.com/en-us/download/details.aspx?id=19125James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

Hi, Please run ExBPA to have a health scan of your Exchange Server. Please install kb953952. A mailbox server becomes intermittently unresponsive for one or more storage groups, and event ID 623 is logged in Exchange Server 2003 http://support.microsoft.com/kb/953952 If the issue still persists, then please run exchsrvr\bin\isinteg -s server1 -fix -test alltests After that, if database has currupt, then I think we need to move mailbox to new information store. Xiu Zhang TechNet Community Support

@Jamestechman - I don't think its a performance problem only because nothing has changed as far as I/O demands. I'm going to try a few of the other suggestions first and if they fail I'll swing back around to this one, thanks! @Xiu Zhang - MSFT - I have run the BPA several times and all is well there. I will try the hotfix tonight and if that fails I'll give the exchsrvr\bin\isinteg -s server1 -fix -test alltests a try and see what I get. Over the weekend I did migrate all mailboxes out of one store and into another and I'm not seeing the error on the new stores. Thanks to both of you!

Any update?Xiu Zhang TechNet Community Support