Disk bottleneck found on disk containing the transaction log files

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at http://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool has determined that the disk system that holds the Exchange Server log files is over tasked and causing a performance bottleneck. This determination is made by checking one or more of the following performance counters:

  • The average Database\Log Record Stalls/sec are more than 10.

  • The maximum Database\Log Record Stalls/sec is more than 100.

  • The average Database\Log Threads Waiting are more than 10.

  • The maximum Database\Log Threads Waiting is more than 20.

If any one of these thresholds is met, an error is displayed stating that your log drive is a disk bottle neck. Log files require a low-write latency. Any backup or stalling in writing to a log file can cause server performance issues. Log stalls may be caused by a low log buffer setting, msExchESEParamLogBuffers, or by too many users connecting to the server.

To reduce log disk latency
  • You can raise the ESE buffers parameter, msExchESEParamLogBuffers, to 9,000. Do not use a value larger than 9,000, as that can corrupt transaction log files. For more information, see Default ESE log buffers have been changed.

  • If a database or transaction log drive is bottlenecked, you can reduce the load on that drive by moving users to a database or storage group that is hosted on a drive that is not near maximum capacity. If all the databases or transaction log drives are nearing capacity, you may have to move users to another server. For more information, see Move User Mailboxes to Another Server.