Re: [Exim] RAM in mail server

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Autor: Richard G. Duvall
Datum:  
To: David Sheryn
CC: Tabor J. Wells, exim-users
Betreff: Re: [Exim] RAM in mail server
I do have this sort of setup (where mail is being delivered to /var/mail
for every user). I did split off the spool to a seperate drive, and that
helped ALOT! I have root filesystem on same drive as /var/mail.

I am thinking of doing the following configuration:

1 wide scsi drive for root filesystem
1 wide scsi drive for spool
2 wide scsi drives striped together, mirrored with 2 other drives which
are striped together.

Total of 6 wide scsi drives. spooling doesn't take that much room, but I
need speed for spooling. But, most of my speed problems are taking place
when people are checking mail, not sending, (unless they are sending to a
user on our system, then it get's queued for later delivery, because it
times out).

This configuration will give us not only redundancy, but more speed
because of the striping, and use of wide scsi, as opposed to narrow on the
same drive as the root filesystem as we have it set up now.

I didn't know about the hierarchy thing in UNIX. I will give that a try.

Is there anybody on this mailing list that can confirm that this hierarchy
thing does make a definite difference in speed on BSDI4.01?

Sincerely,

Richard G. Duvall

On Thu, 19 Aug 1999, David Sheryn wrote:

> On Wed, 18 Aug 1999, Tabor J. Wells wrote:
>
> [ ... ]
>
> > > My hard drive on my mail server is doing alot of access (slow seek time,
> > > etc). I have 10,000 users on the 400Mhz Pentium II with 128MB ram. I am
> > > wondering if my access is being slowed down by mail transfer, or from
> > > swapping. how do I tell which?
>
> [ ... ]
>
> > Also I don't know how your disks are laid out, but I would strongly
> > recommend putting I/O intensive directories (like your mail spool perhaps)
> > and filesystems on their own disk.
>
> If you have a single /var/mail (or whatever) with 10,000 mailboxes in it, then
> this may also be your problem. Unix directories don't scale well to this sort
> of size. You may want to consider splitting the mailboxes accross a directory
> hierarchy e.g. /var/mail/A/B/login where A and B are different for succesive
> login names. Exim has a string expansion function, hash, which may be useful
> for deriving these from the login name.
>
> Regards,
>
> DHS
> -- David Sheryn <D.H.Sheryn@???> Postmaster, Computing Services
> -- City University, Northampton Square, London, EC1V 0HB
> -- Phone: (+44) 171 477 8000 Direct 0171 477 8196 Fax: 0171 477 8565
>
>
>
> --
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