[Jfs-discussion] Fixing damaged superblocks?

[CG M. <lc...@ho...>]

I had a bad power outage that left my Ubuntu 8.04 4x750MB Raid 5 fine 
according to the raid software but damaged according to fsck. I'm hoping 
there might be a way to recover this fs since my primary Superblock 
'SEEMS' almost correct.

First, here's what fsck -v reports:

--------------------------
fsck 1.40.8 (13-Mar-2008)
fsck.jfs version 1.1.11, 05-Jun-2006
processing started: 6/23/2009 22.9.27
Using default parameter: -p
The current device is: /dev/sda1
Open(...READ/WRITE EXCLUSIVE...) returned rc = 0
Invalid data (13) detected in the superblock (P).
Invalid magic number in the superblock (S).
Superblock is corrupt and cannot be repaired
since both primary and secondary copies are corrupt.

CANNOT CONTINUE.
--------------------------

Running the jfs_debugfs utility and displaying the primary sb gives the 
results below which seems to look pretty normal:

----------------------------
[1] s_magic: 'JFS1' [15] s_ait2.addr1: 0x00
[2] s_version: 1 [16] s_ait2.addr2: 0x0000aee4
[3] s_size: 0x00000000fffce838 s_ait2.address: 44772
[4] s_bsize: 4096 [17] s_logdev: 0x00000801
[5] s_l2bsize: 12 [18] s_logserial: 0x0000000a
[6] s_l2bfactor: 3 [19] s_logpxd.len: 8192
[7] s_pbsize: 512 [20] s_logpxd.addr1: 0x00
[8] s_l2pbsize: 9 [21] s_logpxd.addr2: 0x1fffdd3a
[9] pad: Not Displayed s_logpxd.address: 536862010
[10] s_agsize: 0x00400000 [22] s_fsckpxd.len: 16435
[11] s_flag: 0x10200900 [23] s_fsckpxd.addr1: 0x00
JFS_LINUX [24] s_fsckpxd.addr2: 0x1fff9d07
JFS_COMMIT JFS_GROUPCOMMIT s_fsckpxd.address: 536845575
JFS_INLINELOG [25] s_time.tv_sec: 0x48504287
[26] s_time.tv_nsec: 0x00000000
[27] s_fpack: ''
[12] s_state: 0x00000000
FM_CLEAN
[13] s_compress: 0
[14] s_ait2.len: 4
----------------------------

However displaying the secondary sb seems to show a lot of damage as 
seen below:

----------------------------
[1] s_magic: ' ' [15] s_ait2.addr1: 0xff
[2] s_version: 0 [16] s_ait2.addr2: 0xffffffff
[3] s_size: 0x0000000000036000 s_ait2.address: 1099511627775
[4] s_bsize: 256 [17] s_logdev: 0xffffffff
[5] s_l2bsize: 8 [18] s_logserial: 0xffffffff
[6] s_l2bfactor: 0 [19] s_logpxd.len: 16777215
[7] s_pbsize: 85 [20] s_logpxd.addr1: 0xff
[8] s_l2pbsize: 4 [21] s_logpxd.addr2: 0xffffffff
[9] pad: Not Displayed s_logpxd.address: 1099511627775
[10] s_agsize: 0xffffff05 [22] s_fsckpxd.len: 16777215
[11] s_flag: 0xffffffff [23] s_fsckpxd.addr1: 0xff
JFS_OS2 JFS_LINUX [24] s_fsckpxd.addr2: 0xffffffff
JFS_COMMIT JFS_GROUPCOMMIT s_fsckpxd.address: 1099511627775
JFS_LAZYCOMMIT JFS_INLINELOG [25] s_time.tv_sec: 0xffffffff
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: 16777215
----------------------------

Any hope to manually patch it?

TIA

Greg