Am 12.05.25 um 15:39 schrieb DERUMIER, Alexandre: > Am 12.05.25 um 12:57 schrieb DERUMIER, Alexandre: >> for blockdev, do we still use a ceph config file in /var/run for >> potential others rbd client options ? > >>> Not currently, but we can add that later if we consider it worth it. >>> We >>> would need to merge with the storage's already existing ceph.conf and >>> not only write the new options. For now, users can adapt their >>> storage's >>> ceph.conf as desired. > > they still are this rbd_cache_policy for efidisk to fix > https://bugzilla.proxmox.com/show_bug.cgi?id=3329 > > > # SPI flash does lots of read-modify-write OPs, without writeback this > gets really slow #3329 > if ($path =~ m/^rbd:/) { > $var_drive_str .= ',cache=writeback'; > $path .= ':rbd_cache_policy=writeback'; # avoid write-around, > we *need* to cache writes too > } > > > > I'm not sure, but maybe it's fixed in qemu , the biggest problem was > that every single byte write was push to the storage without any buffer > (so it was pretty slow with rbd crush). > but maybe it ok now with: > https://github.com/qemu/qemu/commit/284a7ee2e290e0c9b8cd3ea6164d92386933054f > > (I don't have tested it)
Good point! Unfortunately, it's still very slow without the additional options in current QEMU 9.2 (i.e. even after that commit). I suppose this does require us to have a per-drive configuration already. It's not ideal that qemu-server knows about storage-internal details though and would need to re-write the Ceph config, I might abstract that away by passing an additional $hints parameter or something (e.g. 'writeback-cache' => 1, for EFI disk). We do have a similar situation (but with KRBD): https://lore.proxmox.com/pve-devel/20241025111304.99680-1-f.we...@proxmox.com/ Replying to stuff from your other mail here too: > They are interesting rbd client option that we could add later > https://bugzilla.proxmox.com/show_bug.cgi?id=6290 > crush_location=host:myhost|datacenter:mydc > read_from_replica=localize Those can/should simply be set in the storage's ceph.conf, or do they need to be different per-volume or per-VM? _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
