Hi, Each placement group will get split in 4 pieces in-place all at nearly the same time, no empty pgs will be created. Normally, you only set pg_num, but do not touch pgp_num. Instead, you can set “target_max_misplaced_ratio” (default 5%). Then mgr will increase pgp_num for you. It will increase pgp_num so that some pg get placed into another OSD, until misplaced ratio reached target. Then it wait for some backfilling to finish before increasing pgp_num again. (This behavior seems to be introduced in Nautilus) So I don’t think you need to worry about full OSDs. “backfillfull ratio” should throttling backfill when OSD is nearly full, which in turn will throttling pgp_num increase. 发件人: Gabriel Tzagkarakis<mailto:gabrieltz@xxxxxxxxx> 发送时间: 2021年8月3日 19:42 收件人: ceph-users@xxxxxxx<mailto:ceph-users@xxxxxxx> 主题: PG scaling questions hello everyone, I would like to know how does the autoscale or manual scaling actually works to prevent my cluster from running out of disk space. Let's say i want to scale a pool of 8 PGs each ~400Gb to 32 PGs. 1) does each placement group get split in 4 pieces IN-PLACE all at the same time ? 2) does autoscaling choose one of the existing random placement groups for example X.Y and creates new empty placement groups and migrates data upon them and then continues to the next big PG with or without deleting the original PG? 3) something else ? I am more concerned about the time period when both the initial/pre-existing PGs and the newly created ones co-exist in the cluster to prevent full osds. In my case each pg has many small files and deleting stray pgs takes a long time. Would it be better if i used something like ceph osd pool set default.rgw.buckets.data pg_num 32 and then increase pgp_num in increments of 8 assuming one of the original PGs is affected at a time. But my assumption may be wrong again I could not find something relevant in the documentation Thank you _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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