Topic Last Modified: 2006-09-06
The Microsoft® Exchange Server Analyzer Tool has determined that your Exchange server is not configured for optimal performance.
During regular operation, Exchange servers access various files. The location of the files may contribute to a performance bottleneck. Groups of interdependent files, such as transaction log drives, are also called resources.
If the distribution of these resources contributes to a disk bottleneck, the Exchange Server Analyzer may display a warning or error about the location of the resources on the Exchange server. To make sure that specific resources are isolated from other load demands, put the resources on a dedicated storage device. The following list describes of how each resource is used, including recommendations for how you can configure the resource.
- Transaction log drives The transaction
log files maintain the state and integrity of your .edb and .stm
files. This means that the log files, in effect, represent the
data. There is a transaction log file set for each storage group.
Because transaction logs are a critical backup component for the
data in the Exchange server database files, the Exchange server
must commit all data to the log file before it can finish many of
its transactions on data. Any delays in writing to the transaction
log drive can severely affect the server's performance. Therefore,
it is important that you isolate the transaction log drives so that
the drives have their own disk subsystem that is not shared by any
other server, application, or resource. For best performance, make
sure that each transaction log has a dedicated drive.
- Location of the TEMP drive When first
installed, the operating system sets the temporary file location on
the same drive that is used by the operating system. This means
that any I/O for the TEMP drive competes with I/O for programs and
page file operations that are run from that drive. This competition
for I/O affects performance. The TEMP drive is used for mail
delivery and for the content conversion of large messages. If the
TEMP drive becomes bottlenecked, it will affect mail flow and some
client applications. To avoid having the operating system compete
for I/O with the TEMP drive, and to reduce the risk of performance
issues on the Exchange server, it is recommended that you:
- Change the global environment setting of TEMP to point to
- Move the TEMP drive to its own disk.
- Change the global environment setting of TEMP to point to another disk.
- Location of the .edb and .stm files An
Exchange database consists of two files:
- An .edb file (MAPI content) This file
stores all MAPI messages and tables that are used by the Store.exe
process to locate all messages and checksums of both the .edb and
.stm files and MAPI messages.
- An .stm file (non-MAPI content) This
file contains messages that are transmitted with their native
- An .edb file (MAPI content) This file stores all MAPI messages and tables that are used by the Store.exe process to locate all messages and checksums of both the .edb and .stm files and MAPI messages.
- Location of the SMTP Directory The SMTP
queue stores SMTP messages until Exchange writes them to a database
(the mailbox store or the public folder store) or sends the
messages to another server or connector. Generally, SMTP queues
experience random, small I/Os. The Exchange Server Analyzer
displays a warning if the SMTP directory is on a drive that is
shared by any of the following:
- Any other Exchange data file
- The TEMP or TMP directories
- The page file
- The system drive
- Any other Exchange data file
- Location of the page file The page file
serves as an extension of the physical memory. Specifically, the
page file is where the system stores unused pages or pages that the
system will need later. The page file is always used, even by
servers that have an adequate amount of free memory. This constant
use is because the operating system tries to store only necessary
pages and sufficient free space for operations. For example, a
printing tool that is used only at startup may have some of its
memory paged to disk and never brought back if it is never
In servers where the physical memory is being used heavily, make sure that all access to the page file is as fast as possible. It is recommended that you create a second page file on a drive that is dedicated to the page file.
For More Information
- For more information about Exchange Server performance, see the
Exchange Server 2003 Performance and Scalability Guide
- For more information about troubleshooting Exchange Server
performance issues, see Troubleshooting Microsoft Exchange
Server 2003 Performance (http://go.microsoft.com/fwlink/?LinkId=47588).
- For more information about best practices for designing storage
architectures, see Best Practices Common to Multiple
- For more information about disk sizing, latency, and I/O rates,
see How to Calculate Your Disk I/O Requirements (http://go.microsoft.com/fwlink/?linkid=69747).