Shoot for an average, or let the autoscaler handle it with Think of the PG replica count for a given OSD as the share of the workload it will receive. Larger OSDs naturally will receive more workload.
# The default is way too low ceph config set global mon_target_pg_per_osd 300 # Instruct the balancer to take smaller bites ceph config set global target_max_misplaced_ratio 0.020000 # Guardrail - when you have varying OSD sizes it's easy to overdose # especially when something fails. This does not affect placement, but it # prevents awkward failures of PGs to activate. ceph config set global mon_max_pg_per_osd 1000 # Varying OSD sizes can result in suboptimal balancing by default mgr/balancer/upmap_max_deviation 1 Your list of sizes impliess that you have both mixed-use 3DWPD SSDs and read-intensive 1DWPD SSDs. Is this intentional? I've yet to see a Ceph deployment that indicated the extra cost of MU SSDs, which are the same hardware as RI SSDs, just with a different overprovisioning setting. > On Aug 7, 2025, at 8:08 AM, Albert Shih <albert.s...@obspm.fr> wrote: > > Hi, > > Stupid question but how can I set the number of pg for a pool when I got > differents (1.7 To , 2.7T, 2.9To and 3.4To) size of ssd ? > > Regards > -- > Albert SHIH 🦫 🐸 > France > Heure locale/Local time: > jeu. 07 août 2025 14:06:35 CEST > _______________________________________________ > ceph-users mailing list -- ceph-users@ceph.io > To unsubscribe send an email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io