Many others I’m sure will comment on the snapshot specifics. However running a cluster with some 8TB drives I have noticed huge differences between 4TB and 8TB drives and their peak latency’s when busy. So along with the known snapshot performance you may find the higher seek time and higher TB/disk ratio not helping much.
,Ashley Sent from my iPhone 29 Jun 2017, at 10:43 PM, Stanislav Kopp <stask...@gmail.com<mailto:stask...@gmail.com>> wrote: Hi, we're testing ceph cluster as storage backend for our virtualization (proxmox), we're using RBD for raw VM images. If I'm trying to restore some snapshot with "rbd snap rollback", the whole cluster becomes really slow, the "apply_latency" goes to 4000-6000ms from normally 0-10ms, I see load on OSDs with many read/writes and many blocked processes in "vmstat", after restore is finished everything is fine again. My question is, is it possibly to set some "priority" for snapshot restore, like "nice" so it doesn't stresses OSDs so much? BTW, I'm using ceph 11.2 on Ubuntu 16.04, 4 nodes, with 16 OSDs (8TB each) + Intel 3710 SSD per 4 OSDs for journals. Best, Stan _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com<mailto:ceph-users@lists.ceph.com> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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