Is autoscaler doing the right thing?

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Hello ceph community,

I have some questions about the pg autoscaler.  I have a cluster with several pools.  One of them is a cephfs pool which is behaving in an expected / sane way, and another is a RBD pool with an ec profile of k=2, m=2.

The cluster has about 60 drives across across about 10 failure domains.  (Failure domain is set to “chassis”, and there are some chassis with 4 blades per chassis, and the rest with 1 host per chassis).

The rbd ec pool has 66TiB stored with 128 PGs.  Each PG has about 500k objects in them, which seems like quite a lot.  When rebalancing, this EC pool is always the longpole.

The confusing part is that I am getting inconsistent output on the status on the autoscaler.  For example:

root@vis-mgmt:~# ceph osd pool autoscale-status | grep rbd_ec
rbd_ec                67241G                2.0        856.7T  0.1533                                  1.0      64              on         False  

Which tells me I have 64 PG_NUM (a lie).

root@vis-mgmt:~# ceph osd pool ls detail | grep rbd_ec
pool 4 'rbd_ec' erasure profile ec22 size 4 min_size 3 crush_rule 1 object_hash rjenkins pg_num 128 pgp_num 120 pg_num_target 64 pgp_num_target 64 autoscale_mode on last_change 83396 lfor 0/83395/83393 flags hashpspool,ec_overwrites,selfmanaged_snaps stripe_width 8192 application rbd

Tells me I have 128 PGs (correct), but with a pgp_num which is not a power of 2 (120 pgs).  Also, I am not sure what the pg_num_target and pgp_num_raget are and why they are different from pg_num and pgp_num.

Is there anything I can look into to find out is the autoscaler is working correctly for this pool?  Any other tweaks I need to do?  Seems to me that with that capacity it ought to have more than 128 PGs…

Thank you!

George

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