[CentOS] Corrupt mbr and disk directory map
m.roth at 5-cent.us
m.roth at 5-cent.us
Thu Jan 5 16:20:34 UTC 2012
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
> (boot/root/apps) scsi hard drive. I realized my mistake, but it was
> too late. The system is still powered up and running, but I am sure
> that I have overlaid (and trashed) the mbr and the disk directory map.
<snip>
> I suspect that when I power the system down, it will not reboot. I can
You have that right.
> reinstall mbr and grub, but I don't have the original partition table
> start/end values. Since the system is still running, it seems that the
> partition table must still be available to it from somewhere.
>
> Is there any way to easily restore the partition table?
Easily? No (other than the grub-install /dev/sda part).
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.
Hope that helps.
mark
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