Hi, 

we have done some testing with bluestore and found that the memory consumption 
of the osd 
processes is depending not on the real data amount stored but on the number of 
stored 
objects. 
This means that e.g. a block device of 100 GB which spreads over 100 objects 
has a different 
memory usage than storing 10000000 smaller objects (the bluestore blocksize 
should be tuned for 
that kind of setup). (1000000 objects of size 4k to 100k had a memory 
consumption of ~4GB on the osd 
on standard block size, while the amount of data was only ~15GB). 
So it depends on the usage, a cephfs stores each file as a single object, while 
the rbd is configured 
to allocate larger objects. 

Marcus Haarmann 


Von: "Stijn De Weirdt" <stijn.dewei...@ugent.be> 
An: "ceph-users" <ceph-users@lists.ceph.com> 
Gesendet: Donnerstag, 10. August 2017 10:34:48 
Betreff: [ceph-users] luminous/bluetsore osd memory requirements 

hi all, 

we are planning to purchse new OSD hardware, and we are wondering if for 
upcoming luminous with bluestore OSDs, anything wrt the hardware 
recommendations from 
http://docs.ceph.com/docs/master/start/hardware-recommendations/ 
will be different, esp the memory/cpu part. i understand from colleagues 
that the async messenger makes a big difference in memory usage (maybe 
also cpu load?); but we are also interested in the "1GB of RAM per TB" 
recommendation/requirement. 

many thanks, 

stijn 
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