[PVE-User] Ceph Bluestore - lvmcache versus WAL/DB on SSD

Lindsay Mathieson lindsay.mathieson at gmail.com
Mon Jun 29 16:07:40 CEST 2020


As per the title :) I have 23 OSD spinners on 5 hosts, Data+WAL+DB all 
on the disk. All VM's are windows running with Writeback Cache. 
Performance is adequate but see occasional high IO loads that make the 
VM's sluggish.

With a lot of work I could move the WAL/DB to separate SSD partitions, 
or use lvmcache, which looks to be more transparent to setup.


TBH, write performance could be better, as could IOPS :) The Ethernet 
connections never comes close to being saturated, so I'm guessing write 
speed of the disks is the limiting factor.


I'm tending towards separate WAL/DB devices as I prefer to work within 
the recommended usages of projects such as Ceph these days, rather than 
trying to outguess their design parameters.


Any experiences either way on the list?

-- 
Lindsay



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