Adaptec ATA Raid 1200A upgrade [END GAME]
Dave Ihnat
dihnat at dminet.com
Wed Sep 26 12:15:22 UTC 2007
On Tue, Sep 25, 2007 at 09:58:24PM -0700, Sean Bruno wrote:
> Hmmm...The controller itself failed when copying from the small disk to
> the large disk?
No, it was probably the original last "good" disk failing while writing
and delivering corrupt data to the hardware duplicator. The DiskJockey
doesn't do a drive comparision automatically--it assumes that the source
and destination are good, and only fails the copy if it gets a bad read
indication from the source, or a bad write from the destination. If the
source gives bad data, but doesn't indicate a read error, you get GIGO.
There is a hardware comparison function, but you'd have to run that as
a subsequent pass on the source/data drives.
Why do I suspect the above? Because I tried to run the comparision after
that post, and it failed. Then a recopy failed after reading only about
200Mb from the source--it had finally failed all the way.
My postmortem on this whole thing was that Linux, at that time, knew
nothing about the Adaptec 1200, so it just saw it as a single hard drive,
'hda', when the RAID function was enabled in the controller. This was
good, in that it just ran, while the controller mirrored the data;
it was bad, in the end, because it could never know when one of the
drives in the array had a problem. (since there's no driver in the OS
to read extended functions, such as RAID status, and thus no feedback
from the controller.) The only way to detect a drive failure would be to
periodically reboot the server and watch the Adaptec BIOS messages.
THE END RESULT: I upgraded to the latest version, reinstalled, and
recovered the user/config data from my unpatented-and-free-for-use
removable IDE Hard Drive Backup Unit. (Basically, the only trick is to
use 'hdparm' to allow you to swap the IDE drive, which is in a caddy
in a removable drive bay. The bay/caddy have to be hot-swappable.)
Linux now says it now knows about this controller and offers to build
a RAID array. Don't trust it. It _did_ seem to build an array on the
two new drives, but Grub can't boot from it. I ended up just making a
software RAID in Linux for all data except swap and the boot partition,
turning off the RAID function in the Adaptec and using it just as a
reasonably high-performance ATA100/EIDE controller. I lose a small
bit of the partition on the second disk for the equivalent of the boot
partition, but that's worth it to have congruent configurations (makes
it easier to rebuild a failed drive), and does provide a place to archive
the boot partition. I'll have a cron job periodically copy the real
/boot to the new /bootsave.
It's all good now, except I'm tracking down all the accumulated magic
bits I've developed over the past four years and making sure they work
in the new system. Having a full recovery of the original system makes
this tedious but easy.
All things considered, the Adaptec 1200 is an obsolete controller,
and if I didn't already have it in a system, I'd never use one today.
Cheers,
--
Dave Ihnat
President, DMINET Consulting, Inc.
dihnat at dminet.com
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