On 1/19/20 12:07 PM, Stefan Kooman wrote:
Hi,
Is there any logic / filtering which PGs to backfill at any given time that takes into account the OSD the PG is living on?
Our cluster is backfilling a complete pool now (512 PGs) and (currently) of the 7 active+remapped+backfilling there are 4 of them on the same OSD. Which stresses this OSD way more than needed. It would be nice if the selection criteria for which PG to backfill (and / or recover) from would include the OSD as selection criterion in order to spread the load across different OSDs.
Afaik the OSDs decide this themselves. The primary OSD of a PG will negotiate with other OSDs to determine if they can backfill or not. If you set max_backfills to 4 the OSDs will try to use this as much as possible. The MONs do not decide which OSD starts to backfill and which don't. Wido
Gr. Stefan