Ah. Note “average”. These warnings can be a bit alarmist. Please send
`ceph df` `ceph osd dump | grep pool` > On Aug 13, 2025, at 2:24 AM, Vishnu Bhaskar <vishn...@acceleronlabs.com> > wrote: > > Hi, > My cluster is showing this warning > > [WRN] MANY_OBJECTS_PER_PG: 1 pools have many more objects per pg than average > pool volumes_cache objects per pg (34082) is more than 10.0448 > times cluster average (3393) > > > > Thanks and Regards > Vishnu Bhaskar > Acceleron Labs Pvt Ltd > Bangalore, India > > >> On Wed, Aug 13, 2025 at 1:35 PM Anthony D'Atri <a...@dreamsnake.net> wrote: >> >> Cache tiers are deprecated, I strongly advise finding a way to factor it >> out of your deployment. >> >> There was some discussion of this in the past, e.g. >> >> https://ceph-users.ceph.narkive.com/0LxBSHEQ/changing-pg-num-on-cache-pool >> >> The PG to RADOS object ratio isn't necessarily in and of itself a problem, >> as the dynamics of pg_num for a pool depend on the data and the access >> modality. When multiple pools share the same OSDs, there are tradeoffs >> that include what the pools are for, and how much data each stores. RGW >> index pools, for example, need more PGs than their data volume would >> otherwise indicate. >> >> Is your cache pool for sure limited to *only* the SSDs you expect, or does >> it specify a CRUSH rule that also lands on HDDs? >> >> -- the former Cepher known as Anthony >> >> On Aug 13, 2025, at 12:15 AM, Vishnu Bhaskar <vishn...@acceleronlabs.com> >> wrote: >> >> Hi Team, >> >> I have an OpenStack Ceph cluster where the Cinder volumes pool uses a cache >> pool named *volumes_cache*. >> >> Due to performance issues, I observed that the cache pool has fewer PGs and >> a high PG-to-object ratio, approximately 10x higher than normal. For >> instance, one PG contains around 35,000 objects. I am planning to increase >> the PG number for the cache pool. >> >> For the base pool, I was able to increase the PG count without any issues. >> However, for the cache pool, I encountered a warning indicating that a >> force argument is required. In my lab environment, I found that changing >> the cache pool mode to *none* allowed me to modify the PG number. >> >> Since this is my production setup, I would like to know if there is a safe >> and recommended procedure to increase the PG number of a *cache pool* >> without impacting the environment. >> >> Kindly advise on the best approach. >> >> Thanks and Regards >> Vishnu Bhaskar >> Acceleron Labs Pvt Ltd >> Bangalore, India >> _______________________________________________ >> 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 _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
