On Mon, Jan 07, 2013 at 07:20:16PM +0100, Goffredo Baroncelli wrote:
> On 01/07/2013 05:33 PM, David Sterba wrote:
> > It can have as much as 4 superblock backup copies:
> >
> > Superblock offset 0 is 65536 (0x10000, block=16/0x10)
> > Superblock offset 1 is 67108864 (0x4000000, block=16384/0x4000)
> > Superblock offset 2 is 274877906944 (0x4000000000, block=67108864/0x4000000)
> > Superblock offset 3 is 1125899906842624 (0x4000000000000, block=274877906944/0x4000000000)
> > Superblock offset 4 is 4611686018427387904 (0x4000000000000000, block=1125899906842624/0x4000000000000)
>
> Are you sure ?
>
> Regarding the btrfs-progs suite, I looked at the btrfs_read_dev_super():
> [..]
> for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
> bytenr = btrfs_sb_offset(i);
> ret = pread64(fd, &buf, sizeof(buf), bytenr);
>
> Where BTRFS_SUPER_MIRROR_MAX is 3.
My bad, sorry, I was using the values from an old script that computed
the values with a wrong upper limit.
david
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