Date: Tue, 10 Jun 2008 17:01:09 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Erik Trulsson <ertr1013@student.uu.se> Cc: freebsd-questions@freebsd.org, DA Forsyth <iwrtech@iwr.ru.ac.za> Subject: Re: xRAID disks.... Message-ID: <484EA545.8090305@infracaninophile.co.uk> In-Reply-To: <20080610145926.GA66984@owl.midgard.homeip.net> References: <484EACEB.7169.43FE1258@iwrtech.iwr.ru.ac.za> <20080610145926.GA66984@owl.midgard.homeip.net>
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Erik Trulsson wrote:
> On Tue, Jun 10, 2008 at 04:33:47PM +0200, DA Forsyth wrote:
>> Hiya
>>
>> I've had this for a while now and have done many searches for info
>> but have not yet come up with the right question, hence have not got
>> the answer.
>>
>> My main server has an Adaptec IDE raid card. A couple of years ago I
>> took disks that had been a mirror pair on that card out of the server
>> and put them into my test server, not as a raid pair since the test
>> server has no raid hardware.
>>
>> During boot I see this
>> ad0: 19092MB <WDC WD200EB-00CPF0 06.04G06> at ata0-master UDMA66
>> ad1: 76319MB <WDC WD800JB-00ETA0 77.07W77> at ata0-slave UDMA66
>> ad2: 76319MB <WDC WD800JB-00ETA0 77.07W77> at ata1-master UDMA66
>> ad3: 19092MB <WDC WD200EB-00CPF0 06.04G06> at ata1-slave UDMA66
>> ar0: 76319MB <Adaptec HostRAID RAID1> status: BROKEN
>> ar0: disk0 DOWN no device found for this subdisk
>> ar0: disk1 DOWN no device found for this subdisk
>>
>> The pair of ex-RAID disks are ad1 and ad2 and obviously are no longer
>> a raid pair, yet 'something' is telling the ar() driver to try and
>> pair them and failing because there is no raid hardware in that box.
>>
>> Now I am reconfiguring that machine a bit and would like to fix this,
>> both on these existing drives and on the 320MB drive I have just
>> removed from a RAID1 pair and will be putting into the box instead of
>> ad3 (the other 320GB from the pair is in a USB enclosure for other
>> purposes and has not shown any signs of knowing it was in a raid
>> pair)
>>
>> I suspect the raidinfo is stored on the disk somewhere and a suitable
>> 'dd' command can erase it. but where and how?
>
> That kind of information is usually stored last on the disk (where it is
> least likely to be overwritten by filesystems, partitioning info, or boot
> loaders), so if you overwrite the last couple of KBs on those disks you will
> probably be fine.
> (If you want to be certain you can always use 'dd' to nuke all the
> information on the disk. That will take longer time, but you get the extra
> advantage of testing all the blocks on the disk so that they work
> correctly.)
>
> For the first you could do something like:
> dd if=/dev/zero of=/dev/ad1 bs=1m skip=76318
> which should overwrite the last MB of ad1 with zeros.
>
> To erase all of the disk:
> dd if=/dev/zero of=/dev/ad1 bs=1m
It's rather easier and quite a lot less risky to simply do:
# atacontrol delete ar0
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
Kent, CT11 9PW
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