Hello,
I am working on optimization of ceph performance: CPU load vs OSD data
load. Right now I have 576 PGs in total. Three pools: metadata, data,
rbd. Each pool has 192 PGs. data is not used heavily, rbd is in heavy
use. In total 6 OSDs in cluster. I have read recommendation about 100
PGs per OSD. Roughly I do have 100 PGs per OSD. But now it seems that
PGs in data pool are mostly empty while PGs in rbd pool are quite busy.
Would it make sense to increase number of PGs to be 100 per rbd pool per
OSD? Technically it should take some memory and CPU but because other
two pools are virtually stand still it should not make big difference
while improving data placement on OSDs (which is currently somewhat skewed).
So here two questions:
1. Should I increase number of PGs in rbd pool or better leave it where
it is?
2. Wiki says that increase in PGs is not tested and only should be
attempted on empty pool. Date on Wiki is quite old. Is this still an
issue? Is it safe to increase PGs number on 0.49 on pool in use?
Regards,
Vladimir
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