> > We have been running this particular setup for about a year > now... I am happy with the overall performance, however when > things break, they have a tendancy to break badly especially > with MySQL's replication. > > We had a problem with our NFS store dropping out from under the NFS > server* (the DBs were located on the same machine). This > forced a hard restart on the server and when the server would > come back up the replication in MySQL was broken between the > master and slaves (the master had a different replication > point than the slaves, the slaves were requesting a start > position that didn't exist. The worst part is we didn't > realize it initially until updates to users, etc weren't > being seen on the slave servers). This forced us to down the > local database servers (slave database servers). This did > have the advantage of forcing vpopmail to look at the master > server for reads and writes which was a nice fall back > position, but the restoration process was difficult and > depending on the amount of data in the vpopmail database, > very time consuming moving massive database dumps to resync > the databases on the slave servers. > > I have had to do this process about 5 times since we have > started running this setup. Also if you are going to do this, > be sure that when you do a mysqldump of your data (you are > doing that nightly right?;) ) be sure to use the > --master-data option so the slaves will know where to pick up > replication with the master. Another tip... Turn off auth > logging to mysql if you are doing replication... ICKY.
Thanks for the info! How do you find NFS performance? (Did you use any special tweaking/mount options?) And what are you using for auth?(NIS/LDAP etc) > > We are currently looking at a load balancer solution > (UltraMonkey/LVS or Foundry ServerIron, I would like to consider a Linux alternative, but majority of our support staff are not Linux savvy... > still haven't decided > but UltraMonkey/LVS is working well so far) with DRBD > (http://www.drbd.org/) and heartbeat for both the database > and NFS servers and cheap clones as the actual mail servers > running a combination of qmail+vpopmail+clamav+spamassassin. Just out of interest - What are you using to sync data(configs etc) - You also mention NFS "servers"...So I assume you are running more than one behind a loadbalancer...how are you synching data between them? Regards, MB
