Does anybody know about GlusterFS & Dovecot?
...Andreas
Time marches on, and I need to continue the service migration. I'd still like to use Dovecot (we're migrating away from Cyrus). I'm assuming the only other alternative without existing shared storage is to use DRBD and a cluster file system to provide the replication, and to ensure Director is enabled. Are there any things to watch for surrounding this? We tested glusterfs 3.2 a while ago using four storage nodes, four Dovecot/Postfix machines, and a number of email client bots that generated upwards of a 180k inbound messages per hour, and upwards of 360k pop/imap connections per hour. Unfortunately we did not grab any metrics on how long it took for a POP/IMAP session to open/read/delete/close or how long SMTP transactions took, we simply wanted to see how much load would be generated which was reasonable for
On 9/17/13 3:23 PM, Andreas Gaiser wrote: the machines we used. All storage and mail machines were virtual (vmware) and consisted of 2vcpu with 8gigs mem running Centos 6.1. We tested both NFS and the gluster native client and didn't see much difference in perceived load on the system. We did not run into any of the issues that are common with running Dovecot over NFS during our testing, which we attribute to a proper configuration for NFS and solid NTP. We ran an extended test that lasted for about two months and nothing really hiccuped or failed to function so I would call it a success to that extent.
We also tested stretching the glusterfs cluster between our two data centers which are 100 miles apart as the fiber lays. Our latency is very low and stable between sites, and resulted in a small increase in load on the cluster. I would not recommend this concept over anything but the most stable and fault tolerant WAN imaginable, but it seemed to work reasonably well for the duration of the testing we did (about a day long test).
If I were to do it again obviously I would grab metrics and compare it to access times for a basic single server system on local disk and an NFS backed system using multiple servers, but alas we were just propping it up for fun and see how far we could abuse it. If one could assume that Glusterfs does scale linearly with more nodes you could continue to add capacity to the storage layer and grow the cluster, but that's another level of testing all together.