Hi, We're running mysql in multi-master cluster (galera), mysql standalones, postgresql, mssql and oracle db's on ceph RBD via QEMU/KVM. As someone else pointed out it is usually faster with ceph, but sometimes you'll get some odd slow reads.
Latency is our biggest enemy. Oracle comes with an awesome way to capture an insane amount of perf stats and through that we can see that our avg. latency for writes are ~12ms and reads slightly higher around 15ms. In our usecase that is acceptable. If we used local [SSD] disks this would be much lower (< 1-2ms). We've also experienced once that our galera cluster went out of sync due to a very stressed cluster/network (this particular cluster is satuated every now and then - both disk and network). We had to change scheduler from cfq -> deadline on most db-servers to get acceptable speeds or we encountered writes taking up to 2sec whenever lots of seq. data had to be written. I wouldn't run super high precision/performance databases on it though. Your db performance will always reflect the status of your entire cluster system. I'd say for anything not requiring extremely finetuned always-consistent access times it runs very well. At the very least if you plan to do that, I'd suggest finding some way to isolate and gurantee performance for your guests no matter how busy your cluster would be (which I don't think you can do). We run with SSD journals and SSD backends for most of our db-stuff as we found using normal platter disks as backend could cause some issues if we hit a spikey period of cluster activity (even with ssd journals). Cheers, Martin On Thu, Apr 3, 2014 at 8:04 PM, Brian Beverage < bbever...@americandatanetwork.com> wrote: > I am looking at setting up a Ganeti cluster using KVM and CentOS. While > looking at storage I first looked at Gluster but noticed in the > documentation it does not allow Live Database files to be saved to it. Does > Ceph allow the use of LIVE database files being saved to it. If so does the > database perform well? We have a couple Database servers that will be > virtualized. I would like to know what other Ceph users are doing with > their virtual environments that contain databases. I do not want to be > locked into a SAN. I also would like to do this without being locked into a > proprietary VM software. That is why Ganeti and KVM was the preferred > software. > > > > Thanks, > > Brian > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >
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