The software "appears" to be very inefficient
I have a site like that, really don't know what's up with it.
but I am not sure if it is the way that we have it configured. We're handling between 25k and 30k messages a day (~18k local
you mean IMail-user-to-Imail-user local-delivery msgs?
10k outbound)
how about from internet to Imail?
In any case 30k/day what/where ever is only 1 msg every 3 seconds, or 1200 mgs/hour. actually a very light load, even if compressed into business hours.
with Win2k on a dual P3-933Mhz, 512MB memory, on 2 Ultra-160 SCA SCSI drives configured with RAID1. IMail is configured to use the registry for lookups, containing approx 2k domains. The spool and mailboxes are currently stored on the same partition, but I'm not seeing the disc read/write queues reach levels to warrant changing this.
do you de-frag and prune that overloaded partition continuously?
The problems we've had are always to do with CPU time used by either the smtpd32.exe or smtp32.exe processes.
where and what brand of DNS is used by Imail? are the smtp processes hung up waiting for DNS responses?
In the last month, the server CPU usage has been averaging 93%, starving the web interface of CPU time - it looks very bad when it takes up to 5 seconds for the web login page to display.
how many simultaneous webmail users?
My experiments with PerfMon show that disc I/O is not a bottleneck at all, it is always lack of CPU resources.
ok
It can mainly be attributed to smtp32.exe delivering messages, as these processes are at times using 47% CPU each. It seems to spend an awful lot of time (subjective) making registry lookups (watching with Process Explorer from sysinternals.com)... I'm in the process of trying to get a Win32 API profiler working, to see where smtp32.exe is spending most of that CPU time;
seems like you've got it narrowed down. smtp sending and smtpd receiving along with POP/IMAP access "should" be limited only by disk i/o, not by CPU. the fact that you've apparently seen CPU-bound is backwards. webmail is a CPU killer and eats a lot of disk for scanning the .mbx files, and MIME en/de-coding.
what is your max mailbox size?
but having some problems with getting APIMon working atm.
The registry is supposed to be very fast, a self-balancing b-tree, IIRC. any query should take 2 accesses, or 3 max, mitigated by caching.
does you SCSI controller have any cache?
I have other non-IMail boxes handling over 250k messages a day on much lower-spec hardware. * Is the registry a known bottleneck for IMail? Should I consider writing a DLL to move over to SQL?
SQL/odbc overhead can't possibly be faster than registry db.
* Could I perhaps modify IMail such that the web interface runs on a different server from where the mailboxes are stored?
There are webmail servers that will POP/IMAP across tcp/ip, but I haven't seen anybody here reporting great success in moving webmail from Imail box to other boxes.
can you pop in another 0.5 GB of RAM?
Len
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