Alistair Grant posted on Tue, 08 Dec 2015 06:55:04 +1100 as excerpted: > On Mon, Dec 07, 2015 at 01:48:47PM +0000, Duncan wrote: >> Alistair Grant posted on Mon, 07 Dec 2015 21:02:56 +1100 as excerpted: >> >> > I think I'll try the btrfs restore as a learning exercise, and to >> > check the contents of my backup (I don't trust my memory, so >> > something could have changed since the last backup). >> >> Trying btrfs restore is an excellent idea. It'll make things far >> easier if you have to use it for real some day. >> >> Note that while I see your kernel is reasonably current (4.2 series), I >> don't know what btrfs-progs ubuntu ships. There have been some marked >> improvements to restore somewhat recently, checking the wiki >> btrfs-progs release-changelog list says 4.0 brought optional metadata >> restore, 4.0.1 added --symlinks, and 4.2.3 fixed a symlink path check >> off-by-one error. (And don't use 4.1.1 as its mkfs.btrfs is broken and >> produces invalid filesystems.) So you'll want at least progs 4.0 to >> get the optional metadata restoration, and 4.2.3 to get full symlinks >> restoration support. >> >> > Ubuntu 15.10 comes with btrfs-progs v4.0. It looks like it is easy > enough to compile and install the latest version from > git://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git so > I'll do that. > > Should I stick to 4.2.3 or use the latest 4.3.1? I generally use the latest myself, but recommend as a general guideline that at minimum, a userspace version series matching that of your kernel be used, as if the usual kernel recommendations (within two kernel series of either current or LTS, so presently 4.2 or 4.3 for current or 3.18 or 4.1 for LTS) are followed, that will keep userspace reasonably current as well, and the userspace of a particular version was being developed concurrently with the kernel of the same series, so they're relatively in sync. So with a 4.2 kernel, I'd suggest at least a 4.2 userspace. If you want the latest, as I generally do, and are willing to put up with occasional bleeding edge bugs like that broken mkfs.btrfs in 4.1.1, by all means, use the latest, but otherwise, the general same series as your kernel guideline is quite acceptable. The exception would be if you're trying to fix or recover from a broken filesystem, in which case the very latest tends to have the best chance at fixing things, since it has fixes for (or lacking that, at least detection of) the latest round of discovered bugs, that older versions will lack. While btrfs restore does fall into the recover from broken category, we know from the changelogs that nothing specific has gone into it since the mentioned 4.2.3 symlink off-by-one fix, so while I would recommend at least that since you are going to be working with restore, there's no urgent need for 4.3.0 or 4.3.1 if you're more comfortable with the older version. (In fact, while I knew I was on 4.3.something, I just had to run btrfs version, to check whether it was 4.3 or 4.3.1, myself. FWIW, it was 4.3.1.) -- 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
