... I am quite happy now with the performance of that new server I am preparing.
See thread "Intel(R) C600 SAS Controller" for that story: https://www.mail-archive.com/gentoo-user@lists.gentoo.org/msg146119.html Right now I get quite good results when doing backups of the 2 existing VMs (which have their virtio-disks on LVM-LVs on the host) ... up to 200MB/s ... I can show for reference, if someone is interested. I think that is around the possible maximum. ---> The issue I want to share with you is related to a btrfs subvol I have here. Block device sda builds the btrfs-pool containing the root-fs: # btrfs fi show Label: ROOT uuid: 9133c469-df1e-45f5-a09f-d1b9c75c69da Total devices 1 FS bytes used 29.47GiB devid 1 size 500.00GiB used 278.04GiB path /dev/sda Btrfs v3.12 These are the subvolumes (I could/should rm some, but it doesn't matter for this issue, afaik): # btrfs su list / ID 257 gen 4282 top level 5 path __active ID 258 gen 4874 top level 5 path __active/root ID 266 gen 4772 top level 258 path images ID 267 gen 838 top level 258 path images/otrs ID 289 gen 4285 top level 258 path images/windows ID 538 gen 4874 top level 5 path __active/virt-backup fstab has: # grep btrfs /etc/fstab LABEL=ROOT / btrfs defaults,noatime,compress=lzo 0 0 LABEL=ROOT /mnt/virt-backup btrfs compress=no,noatime,subvolid=538 0 0 ... so I want to mount subvolid 538 with disabled compression (to speed up backups as the files written to it are compressed on the fly via pigz already). But after booting I get that dir mounted with compress=lzo (which is default). # mount | grep btrfs /dev/sda on / type btrfs (rw,noatime,compress=lzo,space_cache) /dev/sda on /mnt/virt-backup type btrfs (rw,noatime,compress=lzo,space_cache) remounting works, though: booze ~ # mount -o remount,compress=no /mnt/virt-backup/ booze ~ # mount | grep btrfs /dev/sda on / type btrfs (rw,noatime,space_cache) /dev/sda on /mnt/virt-backup type btrfs (rw,noatime,space_cache) BUT it remounts / without compression as well ... ! Is it a bug? A mistake or misunderstanding? Could someone test this on his gentoo-btrfs-box? -- Additional info: # cat /proc/version Linux version 3.12.21-gentoo-r1 ... sys-fs/btrfs-progs-3.12-r1 # btrfs su get-default / ID 258 gen 4886 top level 5 path __active/root # line in grub.cfg mounts default subvol (because no specific subvol is specified) linux /boot/vmlinuz-3.12.21-gentoo-r1 root=UUID=9133c469-df1e-45f5-a09f-d1b9c75c69da ro Thanks, regards, Stefan
