Hi Anthony, On Sat, 18 Apr 2026, Anthony D'Atri via ceph-users wrote:

You might just periodically set them to warn, capture the info, and turn it back off. But I do have to ask, is there a specific reason you aren't using the autoscaler? It's much better than it used to be, and there are really great improvements in the pipe.

The only reason setting mode=off is the observed ping-pong. The index pool is small (3 GiB stored) and PG merge/split is fast (~3 minutes). Right after adjusting pg_num (to 32/64) the health warning flips into the opposite, several times, back and forth. The SSD-OSD's size is only 32 GiB, 4 per host and 3 hosts. The small size and count was chosen out of unawareness (pre-created LVs). Cloud this be something that confuses the autoscaler?

What you're thinking of is the per-pool threshold. Historically this has defaulted to 3.0 : the autoscaler won't make a change until the calculated value varies by more than a factor of 3 from the current setting. I think of this as hysteresis, but there's probably a better term. There's been some fairly recent work to do this more surgically, which I _think_ removes the per-pool threshold, but in any event, I believe that recent autoscaler releases are fairly immune to this flapping.

Thanks for clarification on BIAS and threshold. Yes I meant threshold, but looks like threshold is obsolete long ago (can't find it in the docs[1])? At least for me the autoscaler seems not immune to flapping. Thanks, Sascha. [1] https://docs.ceph.com/en/latest/rados/operations/pools/#setting-pool-values