looks like well rebuild the cluster when bluestore is released anyway. thanks!
On Tue, Jun 14, 2016 at 7:02 PM Christian Balzer <ch...@gol.com> wrote: > > Hello, > > On Wed, 15 Jun 2016 00:22:51 +0000 pixelfairy wrote: > > > We have a small cluster, 3mons, each which also have 6 4tb osds, and a > > 20gig link to the cluster (2x10gig lacp to a stacked pair of switches). > > well have at least replica pool (size=3) and one erasure coded pool. > > I'm neither particular knowledgeable nor a fan of EC pools, but keep in > mind that the coding is dictated by the number of OSD nodes, so 3 doesn't > give a lot of options, IIRC. > In fact, it will be the same as a RAID5 and only sustain the loss of one > OSD/disk, something nobody in their right mind does these days. > > > current plan is to have journals coexist with osds as that seems to the > > be safest and most economical. > > > You will be thoroughly disappointed by the performance if you do this, > unless your use case is something like a backup server with very few > random I/Os. > Any performance optimizations will suggest looking at journal SSDs first. > > > what levels of striping would you recommend for this size cluster? any > > other optimization conciderations? looking for a starting point to work > > from. > > > Striping is one of the last things to ponder. > Not only does it depend a LOT on your use case, it's also not possible to > change later on, so getting it right for the initial size and future > growth is an interesting challenge. > > > also, any recommendations for testing / benchmarking these > > configurations? > > > > so far, looking at > > https://www.sebastien-han.fr/blog/2012/08/26/ceph-benchmarks/ > > bsd rebuilding itself, and maybe phoronix. > > > Those benchmarks are very much out-dated, both in terms of Ceph versions > and capabilities as well as the tools used (fio is the most common > benchmark tool for some time now). > Once bluestore comes along (in a year or so), there will be another > performance and HW design shift. > > Christian > -- > Christian Balzer Network/Systems Engineer > ch...@gol.com Global OnLine Japan/Rakuten Communications > http://www.gol.com/ >
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