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qdii
Tux's lil' helper
Joined: 19 Sep 2009
Posts: 106
Location: Madrid
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 Posted: Sat Jul 02, 2011 5:01 pm Post subject: Recovering a failing hard drive |
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Hey guys,
A friend of mine gave me her laptop to fix, and as far as I can see, its fucked up beyond repair. When I turn it on, the bios displays pops, followed by a black screen and that's about it. The keyboard doesn't respond, the hard drive is severly damaged, and parts of the screen won't display anything. But good news, what she actually wants is her documents back.
So I unsheathed my Gentoo cd, slipped it in and turned the computer in. Luckily, it boots nicely and a shell appears.
Unfortunately
Fdisk informs me that the computer only has one hard drive, which contains two partitions : sda1 is /boot , sda2 is a LVM partition.
As I know the hard drive is failing, I plug an external drive in, and copy the second partition to it
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dd if=/dev/sda2 of=/mnt/key/aina.img
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Some errors appear during the process but a good share of the disk seems to be copied (140GB when the capacity is 160GB makes me optimistic).
Back to my computer, I create a loop device to use the image I just created, and turn the logical volumes on.
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losetup /dev/loop0 /mnt/key/aina.img
vgchange -aly
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lvscan tells me that there are 3 logical volumes lv_root, lv_swap and lv_home. When I try and create their nodes, however, I come across something suspicious:
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localhost qdii # vgscan --mknodes
Reading all physical volumes. This may take a while...
The link /dev/vg_hera/lv_home should had been created by udev but it was not found. Falling back to direct link creation.
The link /dev/vg_hera/lv_swap should had been created by udev but it was not found. Falling back to direct link creation.
localhost qdii # ls -l /dev/vg_hera/
total 0
lrwxrwxrwx 1 root root 27 jul 2 19:39 lv_home -> /dev/mapper/vg_hera-lv_home
lrwxrwxrwx 1 root root 7 jul 2 19:31 lv_root -> ../dm-7
lrwxrwxrwx 1 root root 27 jul 2 19:39 lv_swap -> /dev/mapper/vg_hera-lv_swap
localhost qdii # cat /dev/mapper/vg_hera-lv_home
localhost qdii #
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lv_root seems to be doing okay: I can mount it, access the directories and files but as they don't hold my friend's documents, I just can't be bothered. Neither can I be by lv_swap.
So is there anybody that has an idea?
Any idea welcome ^^
Thanks! |
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NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 54808
Location: 56N 3W
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| Posted: Sat Jul 02, 2011 6:36 pm Post subject: |
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qdii,
Make a drive image with ddrescue. Do not overwrite what you have already recovered, these things usually only get worse.
Your dd command stops at the first error.
ddrescue works very hard to recover data and will not terminate unless it succeeds.
It does a binary search between errors to get all the easy to recover data quickly then goes back to the 'holes' and tries stepping the head in from both sides to have the best chance of getting a successful read.
Such drive failures are often caused by worn spin motor bearings. You can help ddrescue by trying the drive in positions that it does not normally operate in, like on edge or on its side. This enables gravity to help align the bearings for one last read.
ddrescue is slow - keep an eye on its log for progress.
It must have a log file as it uses it to know what data is still to be recovered.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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qdii
Tux's lil' helper
Joined: 19 Sep 2009
Posts: 106
Location: Madrid
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| Posted: Sat Jul 02, 2011 9:04 pm Post subject: |
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Hey 
thank you so much, ddrescue DID the job, so I consider my problem totally solved ! |
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NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 54808
Location: 56N 3W
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| Posted: Sat Jul 02, 2011 9:15 pm Post subject: |
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qdii,
You may only have a 'soft error' on the drive. It may be just one block that the drive cannot read to reallocate. Check it with smartmontools.
If thats the case, a write will force reallocation and the drive might be good for further use.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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