Restoring corrupted partition table - Success
My Windows XP system corrupted the partition table so I can no longer access all of the extended partitions. It is a standard table (not GUID). I have a RAID 1 system with two drives.
After much reading I understand that TI 2012 does not restore the partition table. The partition table was originally created using a linux version of GParted. The disks have three primary and 7 extended partitions. Only the three primary and one extended partition are currently accessible.
1. Is there any way to get TI 2012 to restore the partition table from a month old full backup without destroying the data?
2. If the answer to 1 is no, then if I restore one drive using the month old full backup (which would overwrite the data), could I then copy the first 512 bytes to the other drive and restore the ability to access the current data on that drive? Is there any chance the partition table generated by TI would match the original table generated by GParted? I have not booted the drives since the partition table corruption and would be using recovery media.
GParted was not able to do a data rescue and a scan using the free version of EaseUS didn't yield very impressive results. I would have to purchase the full version of EaseUS as the drives are 640 GB which is way beyond the 1 GB available using the free version.
You could try and boot to your Acronis Rescue Media and perform a MBR /track 0 only restore. Choose full disks and partitions to restore and only select the MBR /track 0 option.
Thanks for the response but I already tried that. I then started researching why it didn't help and eventually ran across 'Technically, restoring Track 0 and MBR will replace everything in Track 0 (the first 63 sectors on the disk) EXCEPT for the partition table and the disk ID. ' that Mark Wharton wrote in http://forum.acronis.com/forum/13539. That was written in 2010 so unless something has changed in TI 2012, I'll need to use a different method. I can go ahead and restore one drive from my backup but that takes several hours and I was hoping for an easier solution. And I don't know if the method I suggested would even work.
Tom:
The partition table would only contain data for the three primary partitions and the first extended partition. Since you can see those already, there isn't anything wrong with your partition table.
The way that extended partitions work is that there is a pointer in the partition table to the first extended partition. The first extended partition contains another partition table in its first 512 bytes that points to the second extended partition; the second contains a pointer to the third, etc. Another way of saying this is that the partitions are "chained" together, so being able to access the last extended partition requires that every preceding partition be working properly. Your first extended partition probably has broken the "chain".
You could try restoring only the first extended partition from your TI backup. Maybe you'll get lucky.
Mark,
Thanks for the very enlightening message. I wasn't able to determine just how the table for the extended partitions was handled. What I did was downloaded TestDisk and it worked like magic. I was planning in the future to use dd in Linux to copy the first 512 bytes to back up the partition table but, after reading your explanation, I now know that is only a partial solution that would not have helped in this situation.
What happened is Windows XP started displaying, and assigning a drive letter to, a hidden (grub4dos boot) primary partition. With many partitions, I didn't want to lose a drive letter to a hidden partition, so I let Windows XP delete the partition after having no success in removing the assigned drive letter (most options were grayed out). I was planning on replacing that partition with a Linux ext partition which Windows would not recognize. I really should know better than trust Windows to mess with the partitions. I'm beginning to trust Linux but having used PartitionMagic and other DOS tools for many years, and knowing that the old DOS partition tables are handled differently than the way Linux handles them, it's taken me a while to accept the Linux tools which can handle today's large drives.
Thanks for your help,
Tom
Tom,
Glad to here you found a solution, and posted the info about it.
I have already downloaded, and will keep TestDisk as part of my collection of disk tools for use when needed.
Once again, thanks, Mark, for the very valuable information that you provide on these forums.
James
Tom:
Good choice with TestDisk. It's a pretty handy tool. I think you'll find that the Linux tools have kept pace with newer developments in disk hardware and the newer partitioning standards. GParted, for example, handles Windows Vista, 7, and 8 partitioning standards as well as the older XP and pre-XP operating systems.
James:
Another handy tool to add to your collection is PartedMagic, which includes GParted, TestDisk, and an amazing collection of repair utilities in a small (~300 MB) bootable ISO. If you have a laptop with wireless, try out the ISO and note that it includes wireless drivers and support for most of the wireless encryption standards, along with the ability to browse Windows networks. It's almost as full-featured as some Linux distros.