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#50803 - 21/12/2001 13:12 Failed SCSI drive in array, can I do anything
andy
carpal tunnel

Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
I bought myself a nice Dell 2300 server on ebay a few months ago. I has a RAID card and space for 6 hot swappable disks.

When I bought the server it had two 9Gb Quantum disks in it. At the time I couldn't afford new disks (the server only cost me $200 and the disks I wanted would have cost three times that amount). Because I didn't want to mess about with silly small partitions I decided to set the two disks up as a striped 18Gb drive.

Unfortunately yesterday I came to regret that decision...

One of the drives died without any warning, with lots of flashing lights and beeping from the server, all very dramatic. So I lost all 18Gb of disk instead of just losing one 9Gb drive.

Of course I have now discovered that I was not backing everything up that I thought I was. I have lost six months of so of photos and other bits and pieces.

I also lost 10Gb of MP3s, but I was working through re-ripping them anyway...

Does anyone have any suggestions as to what I can try to get the data back, other than taking it to a data recovery firm, my photos aren't that important to me...

I'm now about to buy myself 4 18Gb drives so that I can have a 60Gb RAID 5 array this time. I wish SCSI disks were a bit cheaper, I think my next server will have a IDE RAID array instead.
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#50804 - 21/12/2001 13:20 Re: Failed SCSI drive in array, can I do anything [Re: andy]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
If you don't have backups, there is little that you can do all by yourself. There are companies which specialize in resurrecting data from dead disk drives. Depending on how valuable the data was, you could send the drives to one of those companies and have them help you.

You have learned something important: Striping a pair of disk drives does not increase their reliability. In fact, it doubles your chances for a failure, because striping is not redundant.

I once striped a set of three disk drives so that I could get the speed improvements and the convenience of having a single large volume. I found that the speed improvement was miniscule, but I was stupid and simply left the striped set in place, thinking the convenience of the single large volume was worth it. I was wrong, because I lost one of the disk drives, too, and lost the entire array because of it. Fortunately I had plenty of backups, but some people aren't so lucky.

Going to a genuinely-redundant RAID1 or RAID5 configuration, instead of just striping, will prevent the problem in the future (as you have already surmised), but for now there is little you can do to recover the data unless you pay a professional to do the recovery.
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Tony Fabris

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#50805 - 21/12/2001 13:26 Re: Failed SCSI drive in array, can I do anything [Re: tfabris]
andy
carpal tunnel

Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
Thanks Tony, much as I expected.

I have tried the "gentle tap of the drive on the desk" approach to data recovery now. Don't laugh, I have recovered several gig of data from a seemingly completely dead disk before with this method. Obviously not one to try unless you are sure the disk is really dead.

In this case it didn't help though.

The plus side is that it is now nice and quiet here in my home office, boy are the fans in this beast noisy...
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#50806 - 21/12/2001 14:52 Re: Failed SCSI drive in array, can I do anything [Re: andy]
Wire
member

Registered: 11/09/2000
Posts: 143
Loc: Jylland, Denmark
Hi,

I take it that the drive IS really dead, and not just marked offline by the RAID controller. If that is the case, you're SOL.

In case the RAID controller just THINKS the drive is offline (defective), depending on the controller and the signature it uses to mark a drive offline, it could be possible to resurrect your RAID.

I once had a 10 x 9GB RAID0 (stripe) set mark 3 drives offline, because of a power failure. It was quite frustrating, that when the power came back on, there was 90GB less data - the stripe set wouldn't mount. I called A*****c technical support (makers of SCSI and RAID controllers) and asked what to do, but was told there was nothing to do.

Being kinda desperate, I used a non RAID controller and good old Norton Diskedit, and managed to figure out what the differences between the offline and OK drives was (one byte in the first sector, quite easy actually).

After changing that byte, the stripe set mounted nicely ...

But if the drive's dead, so's yer data. All you got is every second cluster of data, which is useless.
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Lars MkII 40gig 090000598

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#50807 - 21/12/2001 17:01 Re: Failed SCSI drive in array, can I do anything [Re: Wire]
andy
carpal tunnel

Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
Thank you, thank you, thank you...

After reading your post I went and checked in the config menus for the RAID (it's the Dell Perc2 controller) and found an option labelled "force on-line". I tried it and it worked, the machine is now up and running with 18Gb of disk again.

Needless to say I am backing up the missing data as I speak.

I must go and find some docs for my RAID controller to find out why it would suddenly mark a drive as offline.


And to think I tossed the drive in the trash earlier today...

I will obviously still be buying myself 4 new 18Gb drives though.


Edited by andy (21/12/2001 17:03)
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#50808 - 21/12/2001 17:05 Re: Failed SCSI drive in array, can I do anything [Re: andy]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
Wow, cool.

I was assuming your drive was really genuinely bad. That was really good advice you just got. Sorry my advice was wrong!

But now you know to back it up.
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Tony Fabris

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