Re: [Exim] RAM in mail server

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Auteur: Tabor J. Wells
Date:  
À: Richard G. Duvall
CC: David Sheryn, exim-users
Sujet: Re: [Exim] RAM in mail server
On Thu, Aug 19, 1999 at 12:21:25PM -0700,
Richard G. Duvall <rgduvall@???> is thought to have said:

> 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 assume you'll make /var/mail your 2 disks striped + mirrored layout and
use the hierarchy scheme to break up the number of files in that
directory. You should get a noticeable performance boost. Likewise going
to wide will certainly improve your performance.

> 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?


It will make a difference in any flavor UNIX. Sticking 10,000 files in a
single directory will take a very long time any time you have a process
that needs to stat that directory. Splitting it into a smaller number of
files per directory will have a great improvement in performance.

You have a couple of different options. You can do as the previous reply
in this thread suggested by storing files in /var/mail/u/us/username or
some similar scheme. Or you can store an individual's mail spool in their
home directory. I've always chosen to do the latter on my large user
systems, but there's no right or wrong way as long as you distribute the
load.

Tabor

-- 
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Tabor J. Wells                                     twells@???
Fsck It!                 Just another victim of the ambient morality