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Date:      Mon, 16 Jun 2008 17:41:08 +0300
From:      Manolis Kiagias <sonic2000gr@gmail.com>
To:        z.szalbot@lc-words.com
Cc:        Bill Moran <wmoran@potentialtech.com>, freebsd-questions@freebsd.org
Subject:   Re: RAID 1 / disk error / Offline uncorrectable sectors
Message-ID:  <48567B84.4020307@gmail.com>
In-Reply-To: <48567664.2070005@lc-words.com>
References:  <48565E7A.50807@lc-words.com>	<20080616085534.ca7524f8.wmoran@potentialtech.com> <48567664.2070005@lc-words.com>

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Zbigniew Szalbot wrote:
> Dear all,
>
> Bill Moran:
>
>>> My understanding is that RAID 1 no longer works because of this
>>> error. There is a bad sector on HD (Offline uncorrectable sectors)
>>> and the best we can do is replace the drive? Does it make sense to
>>> try to turn RAID 1 on ignoring this error (however, this is done in
>>> BIOS so the machine would have to be taken down in order to do
>>> that)? It seems serious enough for me not to ignore it but then I
>>> know close to nothing about HDs.
>>
>> Replace the hard drive.  Every modern hard drive keeps extra space
>> available to "remap" bad sectors.  This happens magically behind the
>> scenes without you ever knowing about it.  Once you've hit
>> "uncorrectable" errors, it means your re-mappable sectors are used
>> up, and that means the drive is on its last legs.
>
>
> Thank you Bill. One last question. RAID 1 is off now (degraded) and 
> the hosting company is asking if I can try to bring it up (to check if 
> it will work). They have given me this link 
> http://www.freebsd.org/doc/en/books/handbook/raid.html. The problem is 
> that as far as I understand we are not using gmirror but RAID 1 turned 
> on in BIOS (although it is also software-based).
>
> Thank you very much in advance!
>
> Zbigniew Szalbot
> www.lc-words.com
>

Hey Zbigniew ;)

I understand you are using the ataraid (ar) driver. I always use 
gmirror, but it seems they pointed you to the right place in the handbook.
Look at section 18.4.3 - you would probably need to do something like:

# atacontrol list

 From the list, get the ATA channel for /dev/ad12 which is the faulty 
one, e.g. ata2

Detach and re-attach (maybe this will reset the state of the drive)

atacontrol detach ata2
atacontrol attach ata2

atacontrol addspare ar0 ad12
atacontrol rebuild ar0

I've done more or less the same with gmirror when I had similar messages 
a few months back. It may work for a few hours/days but it will fail 
again. Have it replaced ASAP.

Manolis




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