Exchange 2007 Perfromance Monitoring

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					Monitoring database counters can help administrators maintain Exchange 2007 mailbox server
health. Microsoft Exchange Server expert Brien Posey explains some important database
counters and threshold values and offers advice on spotting potential mailbox server problems.

MSExchange Database ==> Instances(*)*\Log Generation Checkpoint Depth counter --
There are a few counters you can use to spot database performance problems -- this is the most
important one. If the current process fails, Exchange Server must either undo or redo the process
to keep a partial transaction from remaining in the database. This counter indicates the amount of
work involved in fixing the database if needed.

According to Microsoft, this counter will usually display a value between 20 and 30 for a healthy
Exchange 2007 mailbox server (per-storage group). Higher values may indicate that there is
either a long running transaction (perhaps a message with a very large attachment), or a disk
bottleneck. A higher value isn't considered problematic unless it exceeds 500.

MSExchange Database (Information Store) \ Database Page Fault Stalls/Sec counter -- This
counter is incremented each time the database cache manager allocates a new page from the
database cache. This counter should remain at zero. Higher values indicate that Exchange is not
removing dirty pages from the database fast enough.

MSExchange Database (Information Store)\Log Record Stalls/sec counter -- This counter
tells how many log records Exchange failed to write to log buffers each second because the
buffers are full.

Ideally, this counter should remain at zero most of the time, with an average value of 10 or less.
If you set an alert based on this counter, the threshold value should be set at 100. This is the
highest spike that Microsoft considers acceptable for a healthy server. Higher spikes or averages
greater than 10 may indicate high I/O write latencies.

MSExchange Database (Information Store)\Version Buckets
Allocated counter -- This is a somewhat obscure yet vital
counter to monitor. By default, Exchange 2007 has a maximum of 16,384 version buckets. If
more than 70% of these buckets have been allocated, Exchange is at risk of depleting the version
store. Because of this, the counter should remain at 12,000 or less.

MSExchange Database Instances(*)\I/O Database Reads Average Latency counter and the
MSExchange Database Instances (*)\I/O Database Writes Average Latency counter -- The
database read latency should register as 20 milliseconds or less on average, but spikes of up to 50
milliseconds are acceptable. Database writes take a bit longer, so they should be 50 milliseconds
or less on average. These can spike up to 100 milliseconds, as long as database page fault stalls
are not occurring.

MSExchange Database (Information Store)\Database Cache Hit% counter -- This counter
shows you the percentage of database file page requests that the database cache fulfilled, instead
of having Exchange perform a file operation.
If users are operating in Outlook cached mode, this number should remain above 99%. If the
majority of your clients are operating Outlook online, or if they're accessing Exchange through
OWA, this number should remain above 90%. Lower numbers indicate that the database cache
size is too small. You can usually fix this problem by adding additional memory to the mailbox

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