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SCSI raid 5  FAULT

Posted on 2004-10-19
Medium Priority
Last Modified: 2009-07-29
I have a raid 5 of 4 HDD scsi controlled by an compaq smart array 5300, disk 0 have failed before I change it for a new one, disk 1 have faild too. I replace drive 0 and rebuild, but I can't start OS w2k. I have a SCSI BIOS NOT FOUND error. Please help me.
Question by:juanFalvarado
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LVL 13

Expert Comment

ID: 12354812
A SCSI BIOS NOT FOUND error indicates that you have a problem with your SCSI card (smartarray 5300 controller).   Your controller card has failed.   That error has nothing to do with the disks.   If you cannot hit the function key that brings up the 5300 settings (F2 or F8, I think?) and diagnostics, you're kind of hosed.....    

If I went by my gut, I think your 5300 controller card failed- causing the disk errors first, and then the card finally died altogether.

You need to contact your support vendor for the 5300 and have it serviced.  

If you do not have warranty or contract support, you need to REPLACE the card.  

With two dead disks, your volume is likely unrecoverable- raid5 can survive the loss of one volume but not two.

Expert Comment

ID: 12355784
When you have your card repaired, you need to check if the disks are dead for real. Malfunctioning controller can report errors and disks failing out the array even when the disks are functional. If the two or more disks are dead for real, the array is in most cases lost (exact outcome depends on how severe the damage to the disks is). If disks turn out good, you may be able to somehow reconstruct the array.  

Author Comment

ID: 12359024
The problem isn't de controller card, I check it and works fine, the array rebuild was succesfull, I check and that message "SCSI BIOS not installed" is ok because its send by server array controller that isn´t installed really, the card is controling the array and server not. The real problem is when starting w2k, it send a message of a corrupted file. How could I have access to my logical drive to backup info, I dont want to reinstall , and I dont want to write anything on logical drive. I hope you can help me.
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LVL 18

Expert Comment

ID: 12360953
Well, if you "rebuilt" the array, then chances are that all your data is already trashed, since the first thing a RAID 5 array does when you build it is synch itself....

And CaseyBea - there IS a version of 5 that can support the loss of two drives, though I doubt he's using it here...  Check out RAID 5EE..  I use it on both of my clusters..


Accepted Solution

tmenasco earned 500 total points
ID: 12361140
That "SCSI BIOS NOT FOUND" is completely normal and has nothing to do with the health of the card!

Raid 5 only has enough stripes to support a single disk failure. If you loose two disks, you are SOL. That is the reasoning behind running Raid5 with an online spare, when a disk fails, it takes the bad disk offline, brings the spare online and rebuilds the array utilizing the patiry information from the other surviving disks. That usually only takes an hour or so and gives you a buffer of not having to replace the failed drive immediately to restore performance. If you are using an array for the boot partition, don't use Raid5, it kills you on performance, use Raid1 for partitions that have high I/O because it doubles the rate at which data can be retrieved from the disk.
LVL 18

Expert Comment

ID: 12361216
Ahh...  But it also doubles the amount of time it takes to WRITE to the disk...


Expert Comment

ID: 12361306
5300 array controllers have at least 64MB of CACHE, so the write operations are cached and the OS doesn't feel a thing, it sees an instant write. That is why they have CACHE batteries, because vital information remains in the CACHE and must be written for the system to survive a power failure.
LVL 18

Expert Comment

ID: 12362033
Ok, well there are IBM controllers with 256MB of CACHE (why you kept capitalizing that is beyond me), and some of them also have pre-fetch..  What's your point?

Expert Comment

ID: 12362675
What is your point? There are also 5300 series with 256MB on card, that was not my point.

My point was that since these are hardware array controllers and they have large cache's, the operating system will not see the delayed write affect if the cache is utilized correctly.

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