Microsoft KB Archive/893599

= You may experience slow client performance if the version store runs out of memory in Exchange Server 2003 =

Article ID: 893599

Article Last Modified on 10/25/2007

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APPLIES TO


 * Microsoft Exchange Server 2003 Standard Edition
 * Microsoft Exchange Server 2003 Enterprise Edition

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SYMPTOMS
You may experience slow client performance on server that is running Microsoft Exchange Server 2003. Additionally, the following event may be logged in the Application log when you experience slow client performance: Event Type: Error

Event Source: ESE Event

Category: Transaction Manager

Event ID: 623

Description: < > (< >) The version store for instance < > (&quot;< >&quot;) has reached its maximum size of < >Mb. 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: < > Session-context: < > Session-context ThreadId: < >.



CAUSE
This problem occurs if the version store runs out of memory. The version store is used by Extensible Storage Engine (ESE) to track and to manage current transactions. The version store is an in-memory list of changes that are made to the database. The version store is used for roll-back of transactions, for write-conflict detection, and for other tasks. The version store entry for a specific operation is cleaned up only one time when the following conditions are true:
 * The transaction that owns the operation has been either committed or rolled back.
 * All the transactions that are outstanding at the time that the operation was performed have been either committed or rolled back.

Therefore, if a transaction is open for a long time, the transaction prevents version store cleanup. Eventually the version store runs out of memory. When the version store runs out of memory, the 623 event message that is mentioned in the &quot;Symptoms&quot; section may be logged.

The version store may run out of memory for several reasons. In this particular case, an operation on the database has had to move through many empty pages that have not been cleaned up. This causes a transaction to be open for a long time.

ESE will not clean up empty pages if a backup is in progress. Note that the 623 event message is not caused by the backup process. The 623 event message may be logged even if a backup is not running.

If a process is sequentially deleting lots of records or index entries when a backup is occurring in the storage group, all the pages that would have been freed when the records or the index entries are deleted remain in the database. Later, ESE may have to move through these deleted pages during a transaction. This action may take a long time. This action may eventually lead to the 623 event message. Subsequent operations on the database are prevented until more space is available in the version store.

You may see this issue in the DeliveredTo table. The DeliveredTo table contains an entry for each incoming message to the server. This entry remains for up to one hour before the entry is removed. The DeliveredTo table prevents duplicate delivery of messages. If empty pages that are being used by this table have not been cleaned up, the 623 event message may be logged.



RESOLUTION
To resolve this problem, apply the hotfix that is described in this section. This hotfix changes the way that empty pages are examined during a backup. This hotifx makes the cleanup of the DeliveredTo table more efficient. Therefore, the ESE can more easily move through the DeliveredTo table.

Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
Because of file dependencies, this hotfix requires Microsoft Exchange Server 2003 Service Pack 1 (SP1).

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

836993 How to obtain the latest service packs for Exchange Server 2003

File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version            Size    File name --  20-Jun-2005  12:58  6.5.7233.28     2,115,072  Ese.dll 21-Jun-2005 03:00  6.5.7233.28     3,261,952  Mdbmsg.dll 04-Jun-2005 01:56                      3,304  Redir.asp 21-Jun-2005 03:33  6.5.7233.28     5,176,832  Store.exe



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

Additional query words: XADM

Keywords: kbqfe kbhotfixserver kbexchstore kbfix kbbug kbexchange2003presp2fix kbpubtypekc KB893599

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