>With all due respect, however, running 10K domains in a test environment is
>a far cry from running it in a production environment with millions of
>users.
domains and users don't count for anything, it's stricly a question
of quantity of msgs per time. And that will be limited by the disk
i/o bandwidth:
1. receive from SMTPD server process, write msg to queue(disk), read
msg from queue(disk), write msg to mailbox(disk)
2. read msg from mailbox(disk), write msg to queue(disk), read msg
from queue(disk), send msg to SMTP client process
>Any other input on this? Thank you everybody for what you've provided so
>far. I really appreciate your input on this.
For the world champion 25 gb / day Imail system:
assume 10 k / avg msg size gives 2.5 milion msgs day.
(2.5 million msgs/day) / (86400 secs/day) = 29 msgs /sec
But each msg requires at least 3 disk data operations, excluding the
filesystem meta-data.
3 x 29 msgs/sec x 10 kb/msg = 870 kbytes/sec, sustained for every
second of the day and excluding meta-data (file system overheads).
870 kbytes/ sec x 86400 sec/day = 75 gb / day disk i/o, excluding meta-data.
The disk system will be the dominating, limiting factor, so separate
disk controllers + drives for mail queue and mail boxes is essential.
RAID 0 + 1 with the biggest on-board cache you can find (to avoid
actually writing to disk). I know of boards with 128 mb of cache.
You really don't want to try this with one box.
Len
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