> > BTRFS is much better for changing things. It supports things like a "RAID-1" > array where the disks have different sizes (as long as no single disk is > larger than all the others combined there will be no wasted space). Also it > allows removing disks while online.
Is there somewhere that describes how it allocates files to drives? I had an array of 4 bcache volumes - 2 x 500GB + 2 x 2TB, and the 2TB drives were filling up and the 500GB drives were empty. Then I had problems with bcache so I progressively removed each drive and re-added without bcache, with a 2TB drive as the last one, so now it looks like this: size 448.76GiB used 252.00GiB path /dev/sda3 size 448.76GiB used 251.03GiB path /dev/sdb3 size 1.80TiB used 1.19TiB path /dev/sdd3 size 1.80TiB used 713.00GiB path /dev/sdc3 And I assume it's ultimately aiming for some optimal ratio of disk use, but I'm curious about what that ratio is... > > On Sat, 6 Dec 2014, Chris Samuel <[email protected]> wrote: > > > Can't comment on BTRFS. > > > > The RAID5/6 code is very experimental and I wouldn't suggest trying to use > > that functionality for any data you're attached to. Stick to 2 drives, > > and good backups, for btrfs. > > I have servers running BTRFS RAID-1, but so far I haven't even tested BTRFS > RAID-5/6. Right at this moment they are merging patches that should make it > theoretically usable, but I'd rather have someone else test it first. > I'm kind of surprised that RAID[56] is getting more attention than any SSD caching project, which I see as a necessity before I'd contemplate using striped raid levels. bcache solves the problem to some extent, but BTRFS really needs to fully control the cache... Do you know if BTRFS RAID[56] is "proper" RAID, eg striped across all the disks, small writes require read-modify-write, etc? Or is it some fancy RAID[56]-like implementation that avoids some of these shortcomings? I'm using btrfs on all my new home machines now. cp --reflink is really really awesome! James _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
