Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have a failed RAID 5 on a silicon raid chip on and ASUS motherboard. (nothing special) The raid consists of 3 drives. One of the drives died(or at least the RAID chip claims it is invalid) and the machine now freezes when it tries to boot to the raid or even boot to anything else for that matter while the raid is plugged in.

I NEED the information off of this but I don't have 1600 moneys to send it to something like drive savers.

Yes, I know "raid is not backup", but Norton ghost has been lying to me and hasn't done the scheduled drive ghost for a month. Please help.

share|improve this question
    
The OP unfortunately has not edited his answer, but his update is below, as an answer: "The meta data on the drives is messed up. so no matter what I do with the drives it's not going to mount/boot. so how do I repair the metadata?" –  derobert Aug 23 '09 at 8:12

5 Answers 5

http://en.wikipedia.org/wiki/RAID%5F5#RAID%5F5

In theory, you should be able to remove the broken drive, and replace it and get the RAID array to recover the array. RAID is not backup, but the "R" is for "redundant" and it should still apply in this case, unless the array itself is dead.

share|improve this answer

You should be able to boot the raid if you take the damaged drive out even if you don't replace it, it just means you've lost the redundancy. However if two of the drives have issues your in trouble.

share|improve this answer

First, do not fiddle with it. Right now, the data is probably still there, but every time you touch it, you risk changing that.

Second — contact your RAID vendor for recovery procedures and/or tools. For example, I've had the metadata on a 3ware (now AMCC) array get messed up — my fault, PEBKAC — and 3ware support worked with me to repair the mess, including sending tools and reconstructing the metadata. If your vendor can't/won't help you, keep that in mind next time your consider a purchase.

Now, assuming you can not get support from your vendor, I'd first make copies of each disk, block-by-block by moving them (one at a time, and make sure to label so you can put them back to the same connector) to a plain-old SATA controller, and then only work on copies of the disks. Then, with the disk copies, I'd try and see if I could get Linux's MD driver to handle it, by trying to figure out (a) the offset to the first block on each disk and (b) the block size by using a hex dumper such as xxd. Then set up loopback devices if needed (for offsets) and use mdadm --build, definitely in read-only mode! Confirm data is correct, if so, copy data. Save original disks, and maybe copies, for a while Just in Case™

(Come to think of it, there are probably tools to do that all for you)

edit

A quick search for Linux programs (because Linux will likely go around your software RAID, and be able to get to the raw disks):

  • dmraid supports Silicon Image Medley software RAID, though it may be confused if the metadata is borked.
  • testdisk: supposedly will scan for files, no idea if it can handle your SiI software RAID.

Also, if all three disks are readable, recovery will be easier: you won't have to use any parity blocks to read the data, and you will be able to use the parity blocks to figure the array offset/block size/etc.

Quick Googling gives a guide of how to do this: http://www.raidrecoveryguide.com/recovery.html

share|improve this answer

Salmon and Col are correct, but I'll add one other thought to consider. I once bricked a RAID card; the drives themselves (and their data) survived, but I ended up having to get a new RAID controller to recover it.

Just another possibility.

share|improve this answer
    
And pray that you can get the exact same model - they're not necessarily compatible. One of the main reasons not to use RAID 5. –  Michael Borgwardt Aug 19 '09 at 20:04
1  
Absolutely; that's something I discussed with the vendor, and, of course, tracking down a long-discontinued card can be interesting. More proof of the theory of "If it's important, back it up!" –  Adrien Aug 19 '09 at 21:30
    
A good argument for software RAID, IMO. I bet I'll be able to read my Linux MD RAIDs with any random Ubuntu livecd, for for longer than the life of the drives. –  derobert Aug 23 '09 at 7:14
    
... I should clarify: The OS's software RAID, not some random vendor one. –  derobert Aug 23 '09 at 7:16

no, it WILL NOT run with removing one of the drives. the data on the drives is perfectly fine. the metadata (information about the RAID chip, the configuration, stripe size sector start/end and the like) is messed up.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.