[ceph-users] RGW performance with lots of objects

Mark Nelson mnelson at redhat.com
Tue Nov 27 10:28:10 PST 2018


Hi Robert,


Solved is probably a strong word.  I'd say that things have improved.  
Bluestore in general tends to handle large numbers of objects better 
than filestore does for several reasons including that it doesn't suffer 
from pg directory splitting (though RocksDB compaction can become a 
bottleneck with very large DBs and heavy metadata traffic)  Bluestore 
also has less overhead for OMAP operations and so far we've generally 
seen higher OMAP performance (ie how bucket indexes are currently 
stored).  The bucket index sharding of course helps too.  One counter 
argument is that bluestore uses the KeyvalueDB a lot more aggressively 
than filestore does and that could have an impact on bucket indexes 
hosted on the same OSDs as user objects.  This gets sort of complicated 
though and may primarily be an issue if all of your OSDs are backed by 
NVMe and sustaining very high write traffic. Ultimately I suspect that 
if you ran the same 500+m object single-bucket test, that a modern 
bluestore deployment would probably be faster than what you saw 
pre-luminous with filestore. Whether or not it's acceptable is a 
different question.  For example I've noticed in past tests that delete 
performance improved dramatically when objects were spread across a 
higher number of buckets.  Probably the best course of action will be to 
run tests and diagnose the behavior to see if it's going to meet your needs.


Thanks,

Mark


On 11/27/18 12:10 PM, Robert Stanford wrote:
>
> In the old days when I first installed Ceph with RGW the performance 
> would be very slow after storing 500+ million objects in my buckets. 
> With Luminous and index sharding is this still a problem or is this an 
> old problem that has been solved?
>
> Regards
> R
>
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