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

  • From: "Brian Pituley" <bpituley@xxxxxxxxxxxxxxxx>
  • To: <exchangelist@xxxxxxxxxxxxx>
  • Date: Wed, 18 Apr 2007 14:45:14 -0700

You realize that the disk queue is different from queues within
Exchange, right?
Brian Pituley
Director of Information Technology
T: 408-441-3611
F: 408-441-8405
E: bpituley@xxxxxxxxxxxxxxxx <mailto:bpituley@xxxxxxxxxxxxxxxx> 


From: exchangelist-bounce@xxxxxxxxxxxxx
[mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of Jabber Wock
Sent: Tuesday, April 17, 2007 8:15 PM
To: exchangelist@xxxxxxxxxxxxx
Subject: [ExchangeList] Re: Exchange server delivery latency: need help!

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
                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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