Hi, we are doing some tests here with a Kraken setup using bluestore backend (on Ubuntu 64 bit). We are trying to store > 10 mio very small objects using RADOS. (no fs, no rdb, only osd and monitors)
The setup was done with ceph-deploy, using the standard bluestore option, no separate devices for wal. The test cluster spreads over 3 virtual machines, each with 100GB storage für osd. We are now in the following situation (used pool is "test"): rados df POOL_NAME USED OBJECTS CLONES COPIES MISSING_ON_PRIMARY UNFOUND DEGRAED RD_OPS RD WR_OPS WR rbd 0 2 0 6 0 0 0 49452 39618k 855 12358k test 17983M 595427 0 1786281 0 0 0 29 77824 596426 17985M total_objects 595429 total_used 141G total_avail 158G total_space 299G ceph osd df ID WEIGHT REWEIGHT SIZE USE AVAIL %USE VAR PGS 0 0.09760 1.00000 102298M 50763M 51535M 49.62 1.00 72 1 0.09760 1.00000 102298M 50799M 51499M 49.66 1.00 72 2 0.09760 1.00000 102298M 50814M 51484M 49.67 1.00 72 TOTAL 299G 148G 150G 49.65 MIN/MAX VAR: 1.00/1.00 STDDEV: 0.02 As you can see, there are about 18GB data stored in ~595000 objects now. The actual space consumption is about 150GB, which fills about half of the storage. Objects have been added with a test script using the rados command line (put). Obviously, the stored objects are counted byte by byte in the rados df command, but the real space allocation is about factor 8. The stored objects are a mixture of 2kb, 10kb, 50kb, 100kb objects. Is there any recommended way to configure bluestore with a better suitable block size for those small objects ? I cannot find any configuration option which would allow modification of the internal block handling of bluestore. Is luminous an option which allows more specific configuration ? Thank you all in advance for support. Marcus Haarmann
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