On Sunday 04 December 2016 18:24:08 Duncan wrote: > Marc Joliet posted on Sun, 04 Dec 2016 17:02:48 +0100 as excerpted: > > That's a good idea, although I'll probably start with sysrescuecd (Linux > > 4.8.5 and btrfs-progs 4.7.3), as I already have experience with it. > > > > [After trying it] > > > > Well, crap, I was able to get images of the file system (one sanitized), > > but mounting always fails with "device or resource busy" (with no > > corresponding dmesg output). (Also, that drive's partitions weren't > > discovered on bootup, I had to run partprobe first.) I never see that > > in the initramfs, so I'm not sure what's causing that. > > If I understand correctly what you're doing, that part is easily enough > explained. > > Remember that btrfs, unlike most filesystems, is multi-device capable. > The way it tracks which devices belong to which filesystems is by UUID, > universally *UNIQUE* ID. If you image a device via dd or similar, you of > course image its UUID as well, destroying the "unique" assumption in UUID > and confusing btrfs, which will consider it part of the existing > filesystem if the original devices with that filesystem UUID remain > hooked up. > > So if you did what I believe you did, try to mount the image while the > original filesystem devices remain attached and mounted, btrfs is simply > saying that filesystem (which btrfs identifies by UUID) is already > mounted: "device or resource busy". [...] Nope, sorry if I wasn't clear, I didn't mean that I tried to mount the image (can you even mount images created with btrfs-image?). Plus the images are xz-compressed. -- Marc Joliet -- "People who think they know everything really annoy those of us who know we don't" - Bjarne Stroustrup
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