[OpenAFS] is AFS right for me? (mail servers)

Derek Atkins warlord@MIT.EDU
Thu, 14 Oct 2004 18:17:08 -0400

Jerry Amundson <jerry@pbs.com> writes:

> Q1: Can T1 speed adequately support two AFS servers (both being R/W)?


> Current size of the maildir's is 21 GB, but growth is expected.
> Q2: What are practical size limitations of Coda volumes?

What does Coda have to do with anything here?

In AFS, volume size is mostly limited by the amount of time it would
take to move the volume from one server to anotion.

> The general goal is redundancy (of course). If Site 1's T1 is down,
> Site 2 still has access to e-mail, as do any remote users.

Uhh, keep in mind that AFS does NOT support multiple RW replicas.  A
RW volume lives on one and only one server.  This means if a user's
homedir is on server A at site 1 and site 1's T1 goes down, the users
homedir is effectively offline from site 2 or the external internet.
Similarly, if mail arrives at MTA-2 on site 2 for user A while site
1's T1 is down, MTA-2 will NOT be able to store the mail in the user's
maildir, because the maildir will be inaccessible.

> Q3: Each maildir filename is 70 or so char in length. Maximum number of 
> files per directory? Yes, I've *searched* the archives. The only answer 
> I find is something like, "search the archives - it's there".

About 32k files / dir.

> I guess I'll work out more details later - backups, performance, 
> and so on...
> Thanks,
> jerry 


       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord@MIT.EDU                        PGP key available