Very nice. Insightful yet short.

Thanks for the tip.

Exchange-faq.dk - Din portal til Microsoft Exchange Server information

Your pointer to XADM: Log Stalls/sec Are Regularly Greater than 0 (Zero)(http://support.microsoft.com/?id=188676) is helpful. That support article refers to Exchange 5.5. Does the same suggested registry change apply to an Exchange 2000 server?

Thanks.

Donna, In Exchange2000 there is no registry key to increase the log buffers - it is now done by modifying the 'msExchESEParamLogBuffers' value via the ADSIEDIT utility. The default in Ex2000 is 84, however you should manually set the value to 500 (it is not set to 500 in SP3 either).

You should set the value on the 'Information store' & 'storage group' objects for the Exchange server via ADSIEDIT.

Here's how to do it:-

1. Use ADSI Edit to connect to the Configuration Container Naming Context of your Active Directory.
2. Go to the following path:
Configuration Container | CN=Information Store,CN=<server>,CN=Servers,CN=<Admin Group>,CN=Administrative Groups,CN=<org>,CN=Microsoft Exchange,CN=Services,CN=Configuration
3. Right-click the Information Store object, and then click Properties.
4. Change the Select which properties to view drop-down list box to Both.
5. Select the msExchESEParamLogBuffers attribute and type in the value of 500. Although no value will be present, the default will be 84.
6. Remember to click Set after changing the edit field for the attribute.
7. Now (similar steps as 3 - 6) set the msExchESEParamLogBuffers attribute for the individual Storage Group object(s) below the Information Store attribute of the server.
7. Close the ADSI Edit tool by closing the MMC console application.
8. Wait for Active Directory replication to replicate this new value throughout the forest.
9. Restart the Information Store service on the Exchange 2000 server.

Thanks, Mike Smith, for answering the question about setting log buffers in Exchange 2000/3, and my apologies to Donna for referencing an obsolete KB article. An updated article on setting log buffers for Exchange 2000/3 can be found here:

http://support.microsoft.com/?id=328466

Something else to keep in mind when setting the log buffers is that Exchange rounds down whatever you use as a value to the nearest value evenly divisible by 128, with a minimum of 128. Therefore, if you set 500 as the buffer size, the actual number of buffers will be 384. If you set 512, the number of buffers will be 512.

Why then does Exchange set the number to 500 by default? It's a bug, but not a very important one. The functional difference between 384 and 512 buffers is usually negligible.

There have been recommendations made in the past to set the log buffers to 9000. This recommendation does not apply to Exchange 2000 SP3 or later, though there's not much harm in it--you're just wasting some memory.

Each log buffer is 512 bytes in size and buffers one log sector. The maximum value you can set for the buffers is 10240, which will buffer an entire log file (each log file has 10240 sectors in it: 10240 x 512 = 5 MB, which is the file size of a log file).

As a general rule, when playing with the log buffers, start with 512. If your log stalls (mostly) go away from this setting, leave it there. If not, you can increase the buffers in multiples of 128 until the log stalls are relieved. If you get to the max of 10240, and you're still having log stalls, then the next likely suspect for why this is still happening is a disk I/O bottleneck.

FYI, if you have restored from online backup, and you are replaying a large number of transaction log files (thousands of them), you may increase the speed of replay by temporarily changing both the msExchEseParamLogBuffers (to 10240) and msExchEseParamCacheSizeMax (to 307200). Don't forget to set them back to their previous values after you're finished, especially the Cache. If you leave the ESE cache that large (307200 x 4K = 1.2 GB), you may start running out of virtual address space. For more information about memory and buffer tuning for Exchange see this article:

http://support.microsoft.com/?id=815372