Hugo Mills posted on Tue, 21 Feb 2012 01:21:48 +0000 as excerpted: > On Mon, Feb 20, 2012 at 08:13:43PM -0500, Tom Cameron wrote: >> On Mon, Feb 20, 2012 at 8:07 PM, Hugo Mills <hugo@xxxxxxxxxxxxx> wrote: >> > >> > However, you can remove any one drive, and your data is fine, >> > which >> > is what btrfs's RAID-1 guarantee is. I understand that there will be >> > additional features coming along Real Soon Now (possibly at the same >> > time that RAID-5 and -6 are integrated) which will allow the >> > selection of larger numbers of copies. >> > >> > >> Is there a projected timeframe for RAID5/6? I understand it's currently >> not the development focus of the BTRFS team, and most organizations >> want performance over capacity making RAID10 the clear choice. But, >> there are still some situations where RAID6 is better suited (large >> pools of archive storage). > > Rumour has it that it's the next major thing after btrfsck is out > of the door. I don't know how accurate that is. I'm just some bloke on > the Internet. :) The report I read (on phoronix, ymmv but it was supposed to be from a talk at scalex, iirc) said raid-5/6 was planned for kernel 3.4 or 3.5, with triple-copy-mirroring said to piggyback on some of that code, so presumably 3.5 or 3.6. Triple-copy-mirroring as a special case doesn't really make sense to me, tho. The first implementation as two-copy (dup) only makes sense, but in generalizing that to allow triple copy, I'd think/hope they'd generalize it to N-copy, IOW, traditional raid-1 style, instead. I guess we'll see. FWIW, I'm running on an older 4-spindle md-raid1 setup now, and I had /hoped/ to convert that to 4-copy btrfs-raid1, but that's simply not possible ATM tho a hybrid 2-copy btrfs on dual dual-spindle md/raid1s is possible, if a bit complex. Given that the disks are older, 300 gig sata seagates nearing half their rated run-hours according to smart (great on power and spinup cycles tho), now's not the time to switch them to dual-copy-only! I'd think about triple-copy, but no less! Thus, I'm eagerly awaiting the introduction of tri- or preferably N-copy raid1 mode, in 3.5-ish. But the various articles had lead me to believe that btrfs was almost ready to have the experimental label removed, and it turns out not to be quite that far along, maybe end-of-year if things go well, so letting btrfs continue to stabilize in general while I wait, certainly won't hurt. =:^) Meanwhile, I'm staying on-list so as to keep informed of what else is going on, btrfs-wise, while I wait for triple-copy-mode, minimum. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
