> On Tue, 2005-08-02 at 15:38 -0700, Will wrote:
> > Recently when adding another few drives to my raid
> > card I carelessly moved the position of a number
> of
> > drives in a 5 drive raid 5 array. I spent quite a
> bit
> > of time determining the proper order for the
> drives,
> > and I am 95% sure I have it correct. I know for
> > certain the first drive is in the correct position
> > because I can again see the partition table. I can
> > not, however, access the file system.
> >
> > I figured if I ran a read-only JFS fsck I could
> > determine if all of the drives are in the proper
> > order. However, when I try to run the fsck I get
> an
> > error saying that if the device described contains
> a
> > jfs filesystem my primary and secondary
> superblocks
> > must be corrupted.
> >
> > I did a little research (I am fairly new to linux)
> and
> > found the jfs_debugfs command and used it to
> > investigate the file system. I am not really sure
> what
> > I proper jfs file system superblock should look
> like,
> > so I was hoping someone might be able to tell me
> what
> > could be wrong and how I could fix it.
>
> The superblock looks very bad. It almost has no
> resemblance to the jfs
> superblock, except that the s_magic and version
> fields are almost
> correct. What's strange is that the s_magic field
> should be 'JFS1' (all
> capitals). Nearly everything else looks completely
> wrong.
>
> > The ouput is
> > below:
> >
> > jfs_debugfs /dev/sda1
> > jfs_debugfs version 1.1.7, 22-Jul-2004
> >
> > Aggregate Block Size: 4352
>
> This should always be 4096
> >
> > > su
> > [1] s_magic: 'JfS1' [15]
> s_ait2.addr1: 0xff
> s_magic should be 'JFS1'.
> > [2] s_version: 1 [16]
> s_ait2.addr2: 0xffff8b62
> > [3] s_size: 0x0000000074668f78
> s_ait2.address: 1099511597922
> > [4] s_bsize: 4352 [17]
> s_logdev: 0xfffff7fe
> s_bsize should be 4096
> > [5] s_l2bsize: 4 [18]
> s_logserial: 0xffffffd7
> s_l2bsize should be 12
> > [6] s_l2bfactor: 3 [19]
> s_logpxd.len: 16769023
> s_l2bfactor should be 3. It is!
> > [7] s_pbsize: 597 [20]
> s_logpxd.addr1: 0xff
> s_pbsize should be 512
> > [8] s_l2pbsize: 13 [21]
> s_logpxd.addr2: 0xf172e0c2
> s_lpbsize should be 9. Everything after this looks
> like complete
> garbage.
> > [9] pad: Not Displayed
> s_logpxd.address: 1099267498178
> > [10] s_agsize: 0xffdfff05 [22]
> s_fsckpxd.len: 16769713
> > [11] s_flag: 0xefdff6ff [23]
> s_fsckpxd.addr1: 0xff
> > JFS_OS2 [24]
> s_fsckpxd.addr2: 0xf172fe10
> > JFS_COMMIT
> s_fsckpxd.address: 1099267505680
> > JFS_LAZYCOMMIT [25]
> s_time.tv_sec: 0xbd400320
> > 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
>
> The beginning of the superblock has enough
> resemblance to a correct
> superblock to make it look like you have the right
> blocks, but there is
> too much wrong. I know very little about raid.
> Could you be using
> raid3 or raid7? I think the use of byte-size
> striping may explain the
> problem if all 5 disks aren't ordered properly.
>
Alright, if everything look pretty much wrong, then I
image the disks are not in the correct order. I know
for certain that the drives were a raid 5, and they
have the proper stripe size (128K), and I am certain I
have the proper first disk (the partition table only
shows us when one specific disk is in a certain
position). I guess what I will do is try each of the
24 different combinations and record the primary and
secondary superblock data for each configuration.
Is there anything specific I should look for in the
superblock information to give me an idea that I am on
the right track? A parameter that should only have a
small range of values, or a specific value?
Again, I thank you so much for your help so far!
> > display_super: [m]odify or e[x]it: x
> > > s2p
>
> s2p is kind of silly in that it mostly prints the
> same stuff. "sup s"
> will print the secondary superblock.
I will make sure I print the secondary superblock
instead.
> --
> David Kleikamp
> IBM Linux Technology Center
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