On Mon, 15 Jul 2013, Colin Fee wrote:
A most enlightening thread so far. I've begun playing with ZFS within a VM to get used to the various commands and their outcomes etc.
From what I've been reading elsewhere what I like about ZFS is the reduction (or is simplification more appropriate) of something like this (hoping my ASCII art holds up):
[/] [/usr] [/var] [/home] | | | | +---------------------------+ | volume group "vg" | +---------------------------+ | | +-----------+ +-----------+ |PV /dev/foo| |PV /dev/bar| +-----------+ +-----------+ | | | | sda sdb sdc sdd
....to something like this:
[zfs "tank/"] [zfs "tank/usr"] [zfs "tank/home"] | | | +-------------------------------------------------+ | stroage pool "tank" | +-------------------------------------------------+ | | | | sda sdb sdc sdd
You can do that with lvm, by the way. Set up arbitrary redundancy of desired logical volumes too.
One thing I read yesterday was that zfs can be prone to issues from fragmentation - is there a preventive strategy or remedial measure to take into account?
Don't ever use more than 80% of your file system? Yeah, I know that's not a very acceptable alternative. It's funny, with much much reduced memory usage, btrfs has the default bahaviour of caching its free block list (possibly only when running low on space?). ZFS doesn't, so when it start getting low, it has to do a linear search of where to place the next copy-on-write block, so absolutely every single write (including rewrites, this being the brave new world of COW) becomes a painful year long process. -- Tim Connors