On Mon, Mar 30, 2015 at 1:01 PM, Garg, Pankaj <Pankaj.Garg@xxxxxxxxxxxxxxxxxx> wrote: > Hi, > > I’m benchmarking my small cluster with HDDs vs HDDs with SSD Journaling. I > am using both RADOS bench and Block device (using fio) for testing. > > I am seeing significant Write performance improvements, as expected. I am > however seeing the Reads coming out a bit slower on the SSD Journaling side. > They are not terribly different, but sometimes 10% slower. > > Is that something other folks have also seen, or do I need some settings to > be tuned properly? I’m wondering if accessing 2 drives for reads, adds > latency and hence the throughput suffers. You're not reading off of the journal in any case (it's only read on restart). If I were to guess then the SSD journaling is just building up enough dirty data ahead of the backing filesystem that if you do a read it takes a little longer for the data to be readable through the local filesystem. There have been a number of threads here about configuring the journal which you might want to grab out of an archiving system and look at. :) -Greg > > > > Thanks > > Pankaj > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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