Our failure domain is host. We currently have 46 hosts, 6 of them have osds that are weighted down to near 0.
And a correction to my original email, we are using EC 6 + 3 From: Anthony D'Atri <anthony.da...@gmail.com> Date: Tuesday, 19 August 2025 at 2:14 am To: Justin Mammarella <justin.mammare...@unimelb.edu.au> Cc: Ceph Users <ceph-users@ceph.io> Subject: [EXT] Re: [ceph-users] MAX_AVAIL becomes 0 bytes when setting osd crush weight to low value. External email: Please exercise caution How many failure domains do you have? The downweighted hosts, are they spread across failure domains? > On Aug 18, 2025, at 10:28 AM, Justin Mammarella > <justin.mammare...@unimelb.edu.au> wrote: > > Hello, > > We’re seeing the MAX_AVAIL value in ceph df instantaneously drop to 0 Bytes / > 100% full when specific osds have their crush weight > set to low values. > > The osds are otherwise healthy, and ceph osd df does not show their > utilization to be above 70%. > > ceph version 19.2.2 > > CLASS SIZE AVAIL USED RAW USED %RAW USED > mf1hdd 19 PiB 8.9 PiB 10 PiB 10 PiB 53.83 > > to > > POOL ID PGS STORED OBJECTS USED %USED MAX AVAIL > mf1fs_data 1 16384 6.8 PiB 2.51G 10 PiB 100.00 0 B > > We’re running a 9+3 EC pool. > > This cluster has 1139 osds / 46 host. > > We’re in the process of downsizing the cluster and draining nodes via crush > reweight is part of our normal operations. > > It happened once a few weeks ago, and we isolated the issue to the weight on > a single osd. Now it’s happening during rebalance on multiple osds, at some > point the movement of PGs triggers an edge case causing the MAX AVAIL > calculation to fail if the crush weight is too low. > > Example crush weights > > > 1418 mf1hdd 0.02000 osd.1418 up 1.00000 > 1.00000 > > 1419 mf1hdd 0.02000 osd.1419 up 0 > 1.00000 > > 2110 mf1hdd 0.02000 osd.2110 up 1.00000 > 1.00000 > > 2111 mf1hdd 0.02000 osd.2111 up 0 > 1.00000 > > 2112 nvmemeta 0.02000 osd.2112 up 1.00000 > 1.00000 > > > Any ideas before I file a bug report? > > Thankyou > _______________________________________________ > 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
