[ExchangeList] Re: Exchange server delivery latency: need help!

  • From: "Jabber Wock" <jabberwock99@xxxxxxxxx>
  • To: exchangelist@xxxxxxxxxxxxx
  • Date: Tue, 17 Apr 2007 23:14:50 -0400

Hi Praveen,
The disk queue length is zero every time I have checked (ignoring the retry items which are due to external factors such as mis-spelt emails, problem with destination mailservers etc.).  The Active and Ready queues are always zero whenever I have looked, yet users are waiting for their emails for 10 minutes, 20 minutes, sometimes more than 30 minutes!
Backups are taking about 1-2 hours per store, with store sizes of 38GB and 11GB respectively.  This is a single server not multiple servers.
I will try the Mail Transport logging to see if I get any more clues.

On 4/16/07, Praveen Ramaswamy <ramaswamy_praveen@xxxxxxxxx> wrote:
May be checking the disk queue length might give you an idea on your disk performance, This should be less than 2.0 (Avg). Also checking your backup time might help. Usually if there is disk slowness then backup time would also increase. The result might answer why your mailbox movement took so much time.
You have mentioned that not all are complaining! In case you have multiple servers then checking the mail header of the delayed mail will point out to the slow server. You can start your investigation from there.  Even I have a slow disk problem on my server, disk queue length is around 20.0 (Avg) which is very high, database is on the IP SAN. But still mail delivery is in within acceptable time limits. You can also try enabling advanced diagnostic logging on the suspected server for "Mail transport", this puts in more detailed events in the application event and  this also increases load on the server, so you might want to enable this during non-peak hours.
Praveen R

Jabber Wock <jabberwock99@xxxxxxxxx> wrote:
I have an Exchange 2003 server which has started experiencing significant latency (lag) in message delivery in the past 2-4 weeks.  Some users (not all) are reporting that messages are taking many minutes, sometimes 20 minutes to an hour to arrive.  This is true for internal email (sender and recipient both on this Exchanges erver) or external email (emails from outside being delivered to Exchange user, or Exchange user sending to an external user).
I have defragged the store, and also tried moving mailboxes to another store.  I have checked event logs for any clues but don't see anything that would imply an issue.  The queue is typically very small, 50 to 100 messages, all small in size and mostly to non-deliverable external addresses which does not sound like it should be holding up everyone else.  The server typically processes 10000 to 20000 emails per day so a queue of 90 should probably be OK.  RAM usage is less than 50% of physical memory (4GB real, about 1.7GB typically used, store.exe is using maybe 800MB to 1.2GB).  No disk errors or issues in the event log.  The server CPU is a Xeon 3GHz and CPU utiliztion is always quite low, around 10-15%.
This behavior is relatively recent, perhaps in the last 2-4 weeks.  Server traffic has not changed noticeably during that period, i.e. SMTP log files are about the same size they have always been, bandwidth usage is about the same over the past 6 months etc.  Also, not all users are reporting the issue, but there is no obvious pattern to them ( e.g. all on one store, or one OU in the AD etc.).
I did notice that when I was moving mailboxes from one store to another, it was slow as molasses.  It took 3 hours to move 10 mailboxes, none of which were "huge" (maybe 50MB to 300MB in size).  That seems odd, I would have expected the mailbox move (in ESM) to whizz by at amazing speeds especially on a Sunday morning.
Any suggestions as to what I should look at to analyze where the latency in delivery is?  Are there any tools (apart from "Windows Performance Monitor" which I ran but did not show any obvious issues)?  Are there any tuning suggestions for Exchange message delivery?
Any help would be appreciated! (other than "google is your friend" or "go buy some books" thanks LOL).
best regards
J. W.

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