[CentOS] Corrupt mbr and disk directory map
m.roth at 5-cent.us
m.roth at 5-cent.us
Thu Jan 5 20:33:17 UTC 2012
Billy Davis wrote:
> On 1/5/2012 11:20 AM, m.roth at 5-cent.us wrote:
>> Billy Davis wrote:
>>> We are running Centos 5.6. All was fine until yesterday. I attempted
>>> to tar a 14KB work file to a USB floppy (/dev/sdb) for transport to
>>> another server. Unfortunately, I keyed in 'tar cvf /dev/sda filename'
>>> instead of 'tar cvf /dev/sdb filename'. /dev/sda is our main
<tail o' woe elided>
>> Sorry about your problem, but I appreciate the question: it led me to
>> <http://www.cromwell-intl.com/unix/linux-kernel-details.html>, a fair
>> bit of which was quite familiar, and other bits weren't. For example, cat
>> /proc/partitions might give you a serious bit of the information you're
>> looking for.
>>
> Thanks Mark. The cat command provided the lost partition information.
> I used that information with fdisk to restore the partition map. The
> fdisk partition map is now identical to the cat partition information.
Good deal!
>
> Next, I reinstalled grub. All seems normal now, at least until I
> shutdown and reboot. I'll wait until the weekend to do that, just in
> case I still have to do a disk restore for some reason.
Best of luck, and let us know how things turn out.
If things go south, there *are* tools that will let you scan a raw disk,
and you could look for the superblock or the first dup, then calculate
where the fs & partition should start, but that would be *real* work.
>
> Thanks again for your input.
As I said, hope it works.
mark
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