Re: [gentoo-server] ldap or mysql?

[Kirk Hoganson]

I use mysql as a backend for a very busy postfix mail/apache web 
infrastructure.  While the apache setup is really in-house, the mail 
setup is pretty standard.  We serve as a mail host for hundreds of 
domains using a mysql database to house all of the hosted domains and 
user accounts (mail is stored in maildirs). Having the accounts stored 
in the DB allows us to split the mail server tasks across many servers 
(imap, pop, smtp, virus/spam scans, etc.) can be done on different 
servers as the database is replicated to them and can be read locally 
(mail can be passed from system to system which all have a consistent 
DB).  It also eliminates the need for system accounts, which is nice. 
It was a little tricky to get everything setup and working on it's own, 
but it has been just the tool for the job.

We have been using this setup for several years and it has been very 
reliable.

The master/slave relationship needs to be monitored, but generally runs 
well if left to it's own devices.

Failover works well because we have multiple systems and control 
failover between them from a nagios monitoring server (this was some 
cool voodoo but it works really well).

We never considered ldap as an alternative so I can't comment on it's 
performance, but for us, mysql has never been a bottleneck.


paul kölle said the following:
> Hi all,
>
> we are in the process setting up a new server (on gentoo) for the usual
> web/mail/db stuff with cyrus/postfix/apache/mysql/subversion/... We'd
> like to store all accounts in a backend that can be shared by more than
> one host and run in an replicated server/slave setup so that one machine
> can takeover the service if the other fails.
>
> I've looked around and it seems there is a general choice of using ldap
> or mysql for this. I know LDAP and it's shortcomings quite well (hairy
> bdb setup, no transactions) otherwise it should be fine for the job. The
> other option is mysql. You can have system accounts through pam and nss
> modules, there is a backend for SASL, apache can fetch vhosts from mysql
> as well as cyrus and postfix can for mail (if not directly it should
> always work with nss/pam). Unfortunately I have no practical experience
> with mysql for things like that.  I heard about persistent connections,
> caches or connections over sockets but haven't tried anything like that
> (yet). So I'm really interested in real world experiences...
>
> Does it work reliably?
> Does mysql master/slave work reliably?
> How do you handle failover?
> How does it performs in comparison to LDAP in terms of bind/fetch/unbind
> cycle, is that expensive?
> Anything I couldn't ask since I'm sooooooooooooo clueless ;)
>
> thanks
>  Paul
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