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Re: How are alternate superblocks repaired?



Hi Andreas,

Here is the textual difference between the primary (good) superblock and backup (bad) superblock #1 and the xxd hex difference between them:

primarysb-bkupsb1-txt.diff:
< Filesystem features:      has_journal ext_attr filetype sparse_super
---
> Filesystem features:      has_journal filetype sparse_super
8c8
< Filesystem state:         clean
---
> Filesystem state:         not clean
14,15c14,15
< Free blocks:              13907467
< Free inodes:              9246071
---
> Free blocks:              18818929
> Free inodes:              9568245
24,26c24,26
< Last mount time:          Thu Sep 27 23:47:27 2007
< Last write time:          Fri Sep 28 00:20:22 2007
< Mount count:              17
---
> Last mount time:          n/a
> Last write time:          Wed Mar 30 16:59:15 2005
> Mount count:              0
28c28
< Last checked:             Tue Sep 18 06:56:43 2007
---
> Last checked:             Wed Mar 30 16:58:55 2005
30c30
< Next check after:         Sun Mar 16 06:56:43 2008
---
> Next check after:         Mon Sep 26 17:58:55 2005

primarysb-bkupsb1-xxd.diff:
< 0000000: 0000 9200 5edc 2301 d197 0e00 0b36 d400  ....^.#......6..
< 0000010: 7715 8d00 0000 0000 0200 0000 0200 0000  w...............
< 0000020: 0080 0000 0080 0000 0040 0000 4f79 fc46              Oy F
< 0000030: 0681 fc46 1100 1e00 53ef 0100 0100 0000  ...F....S.......
< 0000040: ebae ef46 004e ed00 0000 0000 0100 0000  ...F.N..........
< 0000050: 0000 0000 0b00 0000 8000 0000 0c00 0000  ................
---
> 0000000: 0000 9200 5edc 2301 d197 0e00 7127 1f01  ....^.#.....q'..
> 0000010: f5ff 9100 0000 0000 0200 0000 0200 0000  ................
> 0000020: 0080 0000 0080 0000 0040 0000 0000 0000                  
> 0000030: 3321 4b42 0000 1e00 53ef 0000 0100 0000  3!KB....S.......
> 0000040: 1f21 4b42 004e ed00 0000 0000 0100 0000  .!KB.N..........
> 0000050: 0000 0000 0b00 0000 8000 0100 0400 0000  ................

The Maximum mount count is 30, and I have no reason to believe that e2fsck has ever been run against this particular FC3 ext filesystem.
I have every reason to believe, however, that fsck has been run on occasion when I either boot the FC3 system manually and the mount count is over 30 or when I experience the situation where the ext_attr goes missing and I then manually boot the system when it is not clean in the primary superblock.  The system was created at the end of March, 2005 and as you can see from the differences the backup superblock(s) have never even been touched after their creation.

What parameters do you suggest be used when e2fsck is run to repair the backup superblocks?

-- Tom


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