Hello,
Both the primary and secondary superblocks on one of my volumes were damaged by
corruption of the first 16 blocks of the RAID array. Never good.... I'm still
hoping for a quick fix, so before I recover data from backup I've got a few
questions that I'm hoping someone on this list can help me with.
But first a bit of background on the corruption... fsck.jfs reports invalid
magic numbers for both primary and secondary superblocks:
fsck.jfs -n -v /dev/md12
fsck.jfs version 1.1.14, 06-Apr-2009
processing started: 6/19/2010 1.25.54
The current device is: /dev/md12
Open(...READONLY...) returned rc = 0
Invalid magic number in the superblock (P).
Invalid magic number in the superblock (S).
The superblock does not describe a correct jfs file system.
If device /dev/md12 is valid and contains a jfs file system,
then both the primary and secondary superblocks are corrupt
and cannot be repaired, and fsck cannot continue.
Otherwise, make sure the entered device /dev/md12 is correct.
Here are the damaged superblocks:
jfs_debugfs /dev/md12
jfs_debugfs version 1.1.14, 06-Apr-2009
G
Aggregate Block Size: 4352
> su p
[1] s_magic: 'JfS1' [15] s_ait2.addr1: 0xff
[2] s_version: 1 [16] s_ait2.addr2: 0xfff42cb3
[3] s_size: 0x0000000bd05431b0 s_ait2.address: 1099510852787
[4] s_bsize: 4352 [17] s_logdev: 0xfffff6f3
[5] s_l2bsize: 4 [18] s_logserial: 0xffffffed
[6] s_l2bfactor: 3 [19] s_logpxd.len: 16744447
[7] s_pbsize: 597 [20] s_logpxd.addr1: 0xfe
[8] s_l2pbsize: 13 [21] s_logpxd.addr2: 0x85f4f57f
[9] pad: Not Displayed s_logpxd.address: 1093169116543
[10] s_agsize: 0xfbffff05 [22] s_fsckpxd.len: 16583605
[11] s_flag: 0xefdff6ff [23] s_fsckpxd.addr1: 0xfe
JFS_OS2 [24] s_fsckpxd.addr2: 0x85f7e9c9
JFS_COMMIT s_fsckpxd.address: 1093169310153
JFS_LAZYCOMMIT [25] s_time.tv_sec: 0xb41c8aa9
JFS_BAD_SAIT JFS_SPARSE [26] s_time.tv_nsec: 0xffffffff
DASD_ENABLED DASD_PRIME [27] s_fpack: '???????????'
[12] s_state: 0xffffffff
Unknown State
[13] s_compress: -1
[14] s_ait2.len: 16777211
display_super: [m]odify or e[x]it: x
> su s
[1] s_magic: 'JfS1' [15] s_ait2.addr1: 0xff
[2] s_version: 1 [16] s_ait2.addr2: 0xfff42cb3
[3] s_size: 0x0000000bd055d1b0 s_ait2.address: 1099510852787
[4] s_bsize: 4352 [17] s_logdev: 0xfffff6f3
[5] s_l2bsize: 4 [18] s_logserial: 0xffffffed
[6] s_l2bfactor: 3 [19] s_logpxd.len: 16744447
[7] s_pbsize: 597 [20] s_logpxd.addr1: 0xfe
[8] s_l2pbsize: 13 [21] s_logpxd.addr2: 0x85f4f57f
[9] pad: Not Displayed s_logpxd.address: 1093169116543
[10] s_agsize: 0xfbffff05 [22] s_fsckpxd.len: 16583605
[11] s_flag: 0xefdff6ff [23] s_fsckpxd.addr1: 0xfe
JFS_OS2 [24] s_fsckpxd.addr2: 0x85f7e9c9
JFS_COMMIT s_fsckpxd.address: 1093169310153
JFS_LAZYCOMMIT [25] s_time.tv_sec: 0xb41c8aa9
JFS_BAD_SAIT JFS_SPARSE [26] s_time.tv_nsec: 0xffffffff
DASD_ENABLED DASD_PRIME [27] s_fpack: '???????????'
[12] s_state: 0xffffffff
Unknown State
[13] s_compress: -1
[14] s_ait2.len: 16777211
display_super: [m]odify or e[x]it: x
> q
Here's what a good superblock looks like in my environment:
jfs_debugfs /dev/md10
jfs_debugfs version 1.1.14, 06-Apr-2009
G
Aggregate Block Size: 4096
> su p
[1] s_magic: 'JFS1' [15] s_ait2.addr1: 0x00
[2] s_version: 1 [16] s_ait2.addr2: 0x000bd34c
[3] s_size: 0x0000000bd040b1b0 s_ait2.address: 774988
[4] s_bsize: 4096 [17] s_logdev: 0x0000090a
[5] s_l2bsize: 12 [18] s_logserial: 0x00000010
[6] s_l2bfactor: 3 [19] s_logpxd.len: 32768
[7] s_pbsize: 512 [20] s_logpxd.addr1: 0x01
[8] s_l2pbsize: 9 [21] s_logpxd.addr2: 0x7a0b0a80
[9] pad: Not Displayed s_logpxd.address: 6342511232
[10] s_agsize: 0x04000000 [22] s_fsckpxd.len: 193610
[11] s_flag: 0x10200900 [23] s_fsckpxd.addr1: 0x01
JFS_LINUX [24] s_fsckpxd.addr2: 0x7a081636
JFS_COMMIT JFS_GROUPCOMMIT s_fsckpxd.address: 6342317622
JFS_INLINELOG [25] s_time.tv_sec: 0x4be374d8
[26] s_time.tv_nsec: 0x00000000
[27] s_fpack: 'id-0910451'
[12] s_state: 0x00000000
FM_CLEAN
[13] s_compress: 0
[14] s_ait2.len: 4
display_super: [m]odify or e[x]it: x
> q
Now the questions:
1) Does anyone have suggestions on how to recover the superblocks? Again, I'm
still hoping for a 'quick fix' ;-)
2) It strikes me as odd that the magic number went from 'JFS1' to 'JfS1' (just
a case change on the 'F'). Is this a known problem? Has anyone seen this before?
3) I know the primary super block is 4096 bytes at offset 4096 on the disk...
Where is the secondary superblock? Was my secondary superblock the victim of
the RAID corruption or did JFS replicate the corruption to the secondary block?
I'm guessing the latter because the two superblocks are almost identical.
4) Are there any other copies of the superblock on disk?
Thanks,
Tim
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