[OpenAFS] Advice on using BTRFS for vicep partitions on Linux

[spacefrogg-openafs@spacefrogg.net]

Hi Ciprian,

I use ZFS and BTRFS for hosting volume partitions.

The main ingredient on BTRFS is to disable Copy-on-Write for the respective=
. This also somewhat mitigates surprising out-of-space issues.

You need to provide the 'nodatacow' mount option.

Additionally, depending on your exact setup, you may want to disable write =
barriers (e.g. for network attached storage, 'nobarrier') when it is withou=
t effect.

That's basically it, because, as you pointed out yourself, AFS has only lim=
ited expectations from a filesystem.

You lose data checksumming and compression on BTRFS. So, reasonable RAID co=
nfig and scrubbing may be more important, now.

Last remark. BTRFS, to my knowledge, does not support reservations. You MUS=
T make sure to use a pre-allocated storage for the /vicepX mountpoint or th=
e ugly day of failing AFS writes will come during your next overseas vacati=
on.

ZFS, although you don't want to go that way, works fine as well. Again, mak=
e sure to create a filesystem (i.e. subvolume) with a fixed reservation. AF=
AIK the FS takes care of providing enough space although you cannot disable=
 COW. You keep all the goodies, duplication, deduplication, checksumming. I=
 would suggest reading on ZFS setups for heavy database loads, should I hav=
e got you interested.

I never used compression.

Kind regards,
=E2=80=93Michael