Re: Cloning a Btrfs partition

[Goffredo Baroncelli <kreijack@inwind.it>]

On Thursday, 08 December, 2011 10:00:54 Stephane CHAZELAS wrote:
> Because of the same uuid, the btrfs commands like filesystem
> show will not always give sensible outputs. I tried to rename
> the fsid by changing it in the superblocks, but it looks like it
> is alsa included in a few other places where changing it
> manually breaks some checksums, so I guess someone would have to
> write a tool to do that job. I'm surprised it doesn't exist
> already (or maybe it does and I'm not aware of it?).

The fs-uuid is recorded in the header of every tree block.

>From fs/btrfs/ctree.h

[...]
/*
 * every tree block (leaf or node) starts with this header.
 */
struct btrfs_header {
        /* these first four must match the super block */
        u8 csum[BTRFS_CSUM_SIZE];
        u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
[...]

Moreover I would be worried more about the uuid of the device than the 
filesystem one...




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