On Mon, Jul 16, 2018 at 11:41 PM Christian Wimmer <christian.wimmer@xxxxxxxxx> wrote:
Hi all,I am trying to use Ceph with RGW to store lots (>300M) of small files (80% 2-15kB, 20% up to 500kB).After some testing, I wonder if Ceph is the right tool for that.Does anybody of you have experience with this use case?Things I came across:- EC pools: default stripe-width is 4kB. Does it make sense to lower the stripe width for small objects or is EC a bad idea for this use case?- Bluestore: bluestore min alloc size is per default 64kB. Would it be better to lower it to say 2kB or am I better off with Filestore (probably not if I want to store a huge amount of small files)?- Bluestore / RocksDB: RocksDB seems to consume a lot of disk space when storing lots of files.For example: I have OSDs with about 500k onodes (which should translate to 500k stored objects, right?) and the DB size is about 30GB. That's about 63kB per onode - which is a lot, considering the original object is about 5kB.
Those numbers seem a little large to me (although with erasure coding they could make sense due to the "object info" replication across shards), but in general I would not expect Ceph or RGW to be a good fit for files which tend to be that small from a data storage efficiency standpoint.
That said, you've got about 4TB of data there. Are you sure some large SSDs in a RAID1(+0) or something wouldn't fulfill your needs? ;) If you're more concerned about scaling out the IO than the ratio of data stored to data used, Ceph may still be a good choice. *shrug*
-Greg
_______________________________________________Thanks,Christian
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
