From: by way of Ariel Biener (Ariel)
Date: Tue Jun 01 2004 - 18:56:33 EDT
On Tue, 1 Jun 2004, Ralf Hildebrandt wrote:
> 1. Does any network storage platform come to mind as being
> particularly fast (in terms of "postfix needs to write mails to
> maildir, while clients hammer away using POP3 and IMAP) while being
> reasonably economical?
EMC Cellera NS600/NS700 (with a Clariion backend if you want to save
money), or Netapp F940 and up.
Use GigE links between the servers (postfix/IMAP/POP) and the Netapp/EMC.
Use a dedicated switch to avoid buffering in congested or busy core
network/campus switches.
> Note that the network storage is not exclusively used by us only,
> but is being shared.
>
> 2. Will any NFS solution scale? If not, what alternative is there?
Yes, it will scale, but you must not go cheap on the NAS device, otherwise
it wont.
Just to clarify. We use a distributed system here, 50,000 logins, ~600,000
emails/day. We use the following setup:
Netapp F940, with 4 GigE links, 2 used by other applications, and 2 used
for the mail server farm, in the following manner:
2 mail servers
2 pop readers
1 imap reader
Each of the servers has a GigE link to a dedicated switch, and the
remaining 2 GigE from the Netapp connect to the same switch, and we load
balance by mounting the spool via one GigE and the homedirs via another
(for example, on one mail server we mount the homedirs via the Netapp's
GigE1, and the spool via GigE2, and on the other we do it vice versa).
The servers themselves are actually IBM Blade eServers, sitting in an IBM
blade enclosure (up to 12 servers). Each server is a dual Xeon with 2Gig
ram, connected to the Netapp with one GigE and to the general network with
another.
Now, you can take the above (working) solution, and scale it down to your
mail system size, based on mail traffic/day and number of users actually
accessing the POP/IMAP readers.
Scalability is simple, you throw in another blade, and add it to the load
balancer, either via DNS or via something like Radware or Alteon or
Foundry.
We use Postfix2, WU imap/imaps/pop/pops. If you provide webmail access as
well, I suggest you put it on a separate server (we use Horde/IMP). The OS
is Linux, and we use NFSv3 over tcp. We use hard,intr,lock (mount options).
Please take care to properly tune the Linux system before production
(/etc/sysctl.conf). There are examples and explanations on the Netapp
site, but be conservative about applying, YMMV.
--Ariel
P.S. For an example of out /etc/sysctl.conf and our NFS mount options
> --
> Ralf Hildebrandt Ralf dot Hildebrandt at charite dot de
> my current spamtrap
> http://www.arschkrebs.de/postfix/ Tel. +49 (0)30-450 570-155
> I figure I'll have about 30 kids and six or seven generations down the
> road I'll have my own fair-size nation to rule over. And when we get
> nukes, as we surely shall, we shall wage unlimited war against the
> Empire of Microsoft. -- Joe Thompson
>
> +++++++++++++++++++++++++++++++++++++++++++
> This Mail Was Scanned By Mail-seCure System
> at the Tel-Aviv University CC.
-- Ariel Biener e-mail: PGP(6.5.8) public key http://www.tau.ac.il/~ariel/pgp.html
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