looks like well rebuild the cluster when bluestore is released anyway. thanks!
On Tue, Jun 14, 2016 at 7:02 PM Christian Balzer <chibi@xxxxxxx> 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
chibi@xxxxxxx Global OnLine Japan/Rakuten Communications
http://www.gol.com/
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