Ordinary user comments follow...
On 05/13/2013 08:24 AM, Benedikt Schmidt wrote:
Hi,
currently I'm looking for the correct usage of the force_geometry option
of xfs_repair. I wasn't able to find more documentation on this option
beside that it exists. Could please somebody explain it to me?
According to the xfs_repair man page, it just means to skip the geometry
test. In other words, it's not a place to place CHS values or specify
that your new drive has 4k sectors. Usage is '-o force_geometry'.
For a more detailed description of my problem: I've got here a hard disk
which is dying at the moment, so I copied all the content with dd_rescue
to a new and bigger one. To use xfs_copy wasn't possible as the
filesystem was already corrupted. So now I've got nearly everything on
the second hard disk (dd_rescue could'nt copy something around 6 or 7
MB), but I can not mount the filesystem or even run xfs_repair on it, as
it fails to find a superblock. I think the problem lies in the fact that
the new disk has a different geometry than the previous one.
Kind regards,
Benedikt Schmidt
Did you ddrescue to a regular file or to a new partition? In my case,
ddrescue didn't let me do a simple `ddrescue /dev/sda8 /dev/sdb6`, so I
passed on using ddrescue's suggested '--force' flag and instead did
something like this:
root@plbearer:~# ddrescue /dev/sda8 /mnt/xfstests-test/fs_as_file
GNU ddrescue 1.16
Press Ctrl-C to interrupt
rescued: 671088 kB, errsize: 0 B, current rate: 9043 kB/s
ipos: 671023 kB, errors: 0, average rate: 31956 kB/s
opos: 671023 kB, time since last successful read: 0 s
Finished
# -f means "check a regular file"
# -n means "do not modify filesystem"
root@plbearer:~# xfs_repair -f -n -o force_geometry
/mnt/xfstests-test/fs_as_file
Phase 1 - find and verify superblock...
Phase 2 - using internal log
- scan filesystem freespace and inode maps...
- found root inode chunk
Phase 3 - for each AG...
- scan (but don't clear) agi unlinked lists...
- process known inodes and perform inode discovery...
- agno = 0
- agno = 1
- agno = 2
- agno = 3
- process newly discovered inodes...
Phase 4 - check for duplicate blocks...
- setting up duplicate extent list...
- check for inodes claiming duplicate blocks...
- agno = 0
- agno = 1
- agno = 2
- agno = 3
No modify flag set, skipping phase 5
Phase 6 - check inode connectivity...
- traversing filesystem ...
- traversal finished ...
- moving disconnected inodes to lost+found ...
Phase 7 - verify link counts...
No modify flag set, skipping filesystem flush and exiting.
root@plbearer:~# mount -t xfs -o loop /mnt/xfstests-test/fs_as_file
/mnt/loopback/
With the regular file mounted loopback, this is the part where I would
somehow get the data to a freshly-made XFS filesystem somewhere else,
then verify that the data that I need is indeed still intact and valid.
There are lots of tools to do such operations. I lean on
xfsdump/xfsrestore because I have longstanding good experience with the
programs and see such situations as a really bad time to learn new tools.
If this is your last copy of important data, you should a) use the '-n'
flag of xfs_repair before deciding to modify the ddrescued filesystem,
and/or b) duplicate your recovered filesystem to another place so you
have at least one good emergency backup.
Good luck, and be careful!
Michael
_______________________________________________
xfs mailing list
xfs@xxxxxxxxxxx
http://oss.sgi.com/mailman/listinfo/xfs
