installing big qmail server ... where to start?

[Benson Wong]

I run a qmail-ldap installation for about 10,000 users. Each has 100MB
of quota. I use 2 LDAP servers, 2 qmail servers and have all the
Maildirs stored on a 5.6TB Xserve RAID.

There are a couple of issues you will run into here. 

1. Mass storage. FreeBSD doesn't support file systems > 2TB, at least
not that I found decent documentation and support for.

2. Backing up 50,000 Maildirs, where each email is a separate file
requires something custom. I use Bacula, a network backup tool, and I
instruct it to do a tar-gzip of each Maildir before backup. This adds
a bit of overhead, and almost doubles space usage, but it sure beats
backing up millions of little 4K - 80K files!

3. There is a MAJOR bug with maildirsize, the quota file. These quota
files go out of sync a lot. From a year of statistics about 0.1% of
users will likely have out of sync maildirsize files everyday. Who it
happens to seems to be random. I wrote a custom script that runs every
15 minutes to clean up the out of sync maildirsize files.

Other than those issues my qmail-ldap installation runs super stable.
On the two mail servers I have serving up IMAP and POP3, their load
hovers around 0.1 to 0.3 barely anything at all. On my NFS server the
load is about 0.3... it's barely working too.

Hope that was helpful. 

Ben. 



On 5/4/05, Matthias F. Brandstetter <haimat at lame.at> wrote:
> Hi all,
> 
> I have to plan and setup a mail solution for about 50.000 users, here are
> some key features requested by our customer:
> 
>  - self coded webfrontend w/ webmail and administration (filter, alias etc)
>  - 100MB quota per user
>  - autoresponder
>  - about 50.000 user
>  - online backup of data
>  - some more featuers for web frontend
> 
> Since I happily use qmail for some other (but smaller) installations, I
> want to try it with qmail here for this project as well. My only problem
> is, I have no clue where to start ... beginning from "should I use 2
> redundant and really strong or some more but cheaper servers?" to "which
> qmail distributions and patches should I use (ldap, mysql, ...)?" and "how
> to store data (mails) and do online backup w/o downtime?".
> 
> I know you can't give me _the_ solution for this issue, but I am thankful
> for any hints and internet links on this topic.
> 
> I am sure you guys can help me :)
> Greetings and TIA, Matthias
> 
> --
> And thank you most of all for nuclear power, which is yet to cause a
> single proven fatality, at least in this country.
> 
>   -- Homer Simpson
>      Oh Brother, Where Art Thou?
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