David Gartner <[EMAIL PROTECTED]> wrote:
>
> 4 machines (3 nodes, running qmail, mounting /home from NFS server. 1 NFS
> server--running IDE RAID 5) All four machines: have 64M of ram and a 633
> Mhz proc, have qmail installed, accept smtp and pop3 connections and all
> have the same /home (again, mounted over NFS). Vpopmail is installed on the
> NFS server, in the home directory (local mail is put in
> /home/vpopmail/domains/whatever.com/). /var on each machine is separate, so
> they each have a separate queue. No special concurreny settings. tcpserver
> is accepting 150 connections on pop/smtp at a time. Load balancers in the
> front of these four machines send traffic to the least congested (the nfs
> sever gets less traffic than the other three).
>
> Now, My question is do you think this can support a small ISP (10,000)
> efficiently or should we go with special settings and/or think about
> faster/better hardware? Do you think this leaves room for expansion?
If I was setting it up, I'd probably make the NFS server a separate box (not
accepting any SMTP or POP3 connections), probably running on SCSI RAID instead
of IDE. The faster the SCSI setup, the better, of course. Additional memory
in the NFS server would also be a benefit, and at a cost of USD$50 for 256MB
of ECC PC133 SDRAM, it's hard to justify the business case of _not_ purchasing
one or two extra sticks.
The only other concern I would have would be that if one of your SMTP/POP
toasters dies, you lose the contents of the queue on that machine, since
they're running a single IDE disk for the queue. If this concerns you,
perhaps upgrade each of those machines to IDE RAID.
Can three toasters and one NFS server handle 10,000 users? Probably, but it
depends a lot on what those users are doing. If they're mailing 20MB
attachments to the net at large on a regular basis (or even worse, to each
other), and they're each connected 24/7 and POP-checking their mail every
minute, your systems might fall over rather quickly. If they're mostly dialup
users connected an hour or two a day, sending a few 5k messages each, and only
POP-ing their mail every 15 minutes, maybe your current setup is already
overkill.
You said you were worried -- I wouldn't be. Is the current setup working for
you? Are the toasters frequently hitting their concurrency limits? Do you
have the headroom to raise those limits? Is the NFS server coping with the
current load?
Remember, with a modular architecture like you're using, you can always add
additional toasters in the future, feeding off the same central NFS server.
If you grow to the point that you can't handle it with a single PC-based NFS
server, a NetApp or similar might be within your reach at that point.
Charles
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Charles Cazabon <[EMAIL PROTECTED]>
GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/
Any opinions expressed are just that -- my opinions.
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