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GPT Raid 5 Recovery

Posted: Thu Aug 06, 2009 12:36 am
by Meh
A quick question for the r-studio gurus:

4x1.5TB ICH9R raid 5 array with a single 4.1TB GPT partition went fubar after a Vista 32bit BSoD. The ICH9R BROM shows 2 of the 4 disk as "nonraid member" while the other 2 are detected correctly as members of the raid 5 array. Now there's no way to recover this with 2 missing disks.

The OS drive is not part of the array so there's no problem loading it. I fired up r-studio and the program sees all 4 of the 1.5TB hard drives. Now I know the order of the drives and I know the stripe size but I can't seem to get the offset right. I know Vista uses a 2048 sector offset by default so I tried that... (used this offset on all 4 disks) didn't work. I took a quick look at the FAQ with raid 5 using MBR but it doesn't help me much as the partition is GPT... (I could be wrong, please correct me). So my question is, will r-studio load out the partition automatically without doing a scan if I get the order, stripe size and offset correct for a GPT partition? What if I can't get the offset; is a full scan my only option? Anyone know what the offset would be with this setup so I can try it? It's currently performing a scan right now but it's going to take a long time for 4.1TB of data...

Thanks in advance for your input.

Re: GPT Raid 5 Recovery

Posted: Thu Aug 06, 2009 4:22 am
by Alt
Yes, as soon as R-Studio detects a valid partition, it appears on the Drives pane. No scan is needed. Don't forget to check that Apply immediately is checked, or click the Apply button when you set correct RAID parameters.
About offset. You may find helpful our presentation Finding RAID parameters. ( ... ndex.shtml). Although it deals with a basic Windows partition, you may use it to find the offset.
I recommend you to use R-Studio 64 bit version installed on a 64-bit Windows machine with a lot of memory to better process such a huge RAID. Of course, if such machine is available.

Re: GPT Raid 5 Recovery

Posted: Thu Aug 06, 2009 12:59 pm
by Meh
What is a valid GPT pattern to look for? The scan completed in 17 hours but right after I clicked view files r-studio just hung trying to list the files with the progress bar not moving... I am guess it's because I don't have enough RAM?

Re: GPT Raid 5 Recovery

Posted: Sat Aug 08, 2009 4:25 am
by Alt
Yes, most likely you don't have enough memory to process your RAID completely.

About GPT patterns. Most likely it starts with a standard MBR pattern, 33 C0 8E D0 BC. But not always. You may find more information on Wikipedia: .