[ceph-users] What could cause mon_osd_full_ratio to be exceeded?

[Vladimir Brik]

Hello

I am doing some Ceph testing on a near-full cluster, and I noticed that,
after I brought down a node, some OSDs' utilization reached
osd_failsafe_full_ratio (97%). Why didn't it stop at mon_osd_full_ratio
(90%) if mon_osd_backfillfull_ratio is 90%?


Thanks,

Vlad

[Vladimir Brik]

Why didn't it stop at mon_osd_full_ratio (90%)

Should be 95%

Vlad

Hello
I am doing some Ceph testing on a near-full cluster, and I noticed that,
after I brought down a node, some OSDs' utilization reached
osd_failsafe_full_ratio (97%). Why didn't it stop at mon_osd_full_ratio
(90%) if mon_osd_backfillfull_ratio is 90%?
Thanks,
Vlad
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[Gregory Farnum]

On Mon, Nov 26, 2018 at 10:28 AM Vladimir Brik

Post by Vladimir Brik
Hello
I am doing some Ceph testing on a near-full cluster, and I noticed that,
after I brought down a node, some OSDs' utilization reached
osd_failsafe_full_ratio (97%). Why didn't it stop at mon_osd_full_ratio
(90%) if mon_osd_backfillfull_ratio is 90%?

While I believe the very newest Ceph source will do this, it can be
surprisingly difficult to identify the exact size a PG will take up on
disk (thanks to omap/RocksDB data), and so for a long time we pretty
much didn't try — these ratios were checked when starting a backfill,
but we didn't try to predict where they would end up and limit
ourselves based on that.
-Greg

Post by Vladimir Brik
Thanks,
Vlad
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