Messages in this thread | | | Date | Sun, 31 Oct 1999 15:30:41 -0500 (EST) | From | "Mike A. Harris" <> | Subject | Re: Getting table of partition from one disk? |
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On Sun, 31 Oct 1999, Grégoire Favre wrote:
>I have 3 hard disk in ma machine, one IDE and two SCSI. I just >played with windows 98 and my second SCSI disk come with just >one big (more that 8 Gb) partition instead of the ten little I >had on it (in the order: sdb1:NTFS,sdb2:/boot,sdb3:/usr/src, >sdb5:/data,sdb6:/home,sdb7:fat 16,sdb8:linux swap,sdb9:NTFS, >sdb10:/) and I also know the approximate size of each partitions.
Just some words of wisdom for EVERYONE out there. Immediately after setting up any hard disk, and every time you modify a partition table _ever_, you should IMMEDIATELY do:
dd if=/dev/hda of=/root/hostname-hda-todaysdate.ptbl bs=512 count=1
Where "hda" is the actual device you're backing up, "hostname" is the actual hostname of the machine, "todaysdate" is today's date in some filename friendly, and y2k friendly format.
This backs up the first sector of the device, which is where the partition table exists. Personally, I back up the entire first cylinder instead by changing "count=1" to "count=63".
Note also that any "extended partition tables" should also be backed up too as should any other sectors on disk that indicate some other format of partitioning such as BSD disklabel, and all other things Linux supports.
I'm not aware of any software which does this automatically, however it wouldn't be too hard I don't think to write such software.
>Is there a way to reconstruct the table of partition? >I know that the data are still there: cat /dev/sdb...
Only if you know where the partition boundaries lay. If all partitions are of known formats which you can locate, you can scan the disk looking for the beginning point and end point of the various partitions. I *STRONGLY* recommend duplication of the raw disk with "dd" to an alternate device or backup tape, so that if you hose something while attempting a recovery, you can get another chance.
There is software on Sunsite I believe that will scan your hard disk and try to locate partition beginnings based on "magic" data, and then tell you what it found. I don't know what the program is called though...
>Please, cc all answer to greg@ulima.unil.ch as I am just near dead...
Hang in there! ;o) Disk recovery is very sensitive, it is important to back up the entire disk NOW, before attempting any changes.
>For all of you that have good table of partition: just fdisk p them >and print that, it could be of some use...
Not much. Someone else's partition table would be useless to you. If you don't have partition table backups, your ONLY recourse is:
1) Using software to scan for partitions and recreate them either automatically, or manually afterward.
2) Sending the drive to a data recovery place, which will cost you an arm and a leg.
3) Chocking it up to experience, and making a strong mental note to backup partition tables on every machine you ever get your hands on. ;o)
That is about it...
Good luck! TTYL
-- Mike A. Harris Linux advocate Computer Consultant GNU advocate Capslock Consulting Open Source advocate
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