Replacing dead drives in ZRAID2

[Daniel Kalchev]

Simon,

ZFS is known to put much more stress on hardware than UFS (in typical 
usage) and any flaky hardware setup very quickly breaks up. When I 
started playing with ZFS, I was dismayed that few drives that were 
otherwise perfectly OK and never, ever showed any indication of 
malfunction did show errors with ZFS. Same with controllers.

Just don't panic :)

ZFS is very reliable otherwise, sometimes in the 'magical' realm (but of 
course, don't ever imagine things, when it comes to your data).

My guess is, that you simulated the failing drives by pulling them out 
too quickly. That is, if the Adaptec controller or rather the drives 
doesn't fully support hot-swap you may need to do things more 'safely', 
by waiting a bit between pulls, doing scsi bus reset (and waiting for it 
to enumerate again), rescans etc.

One can sometimes hot-swap even non-hot swappable SATA this way :) 
Sometimes..

Have you tried repeating this experiment?

Daniel

On 03.05.12 01:34, Simon wrote:
> Thank you Mark, that's what I thought, too. My major concern is the failure
> of drives, not so much the hot-swapping. I can live with taking the machine
> offline, replacing the drive(s), and booting up. Yanking the drives out from live
> system is the only way I can simulate a hard failure. Without this working, I
> cannot be sure the system will remain running should a drive go bad. I'm
> not sure how the system would handle this given ahd cannot handle pulling
> of hot drives out.  I will try to get in touch with the driver maintainer.
>
> Thanks again!
> -Simon
>
> On Wed, 2 May 2012 17:21:14 -0500, Mark Felder wrote:
>
>> On Wed, 02 May 2012 17:06:04 -0500,<simon at optinet.com>  wrote:
>>> Having said the above, is there any FreeBSD RAID software I can use with
>>> ahb driver that won't give me same issues I'm experiencing with ahd and
>>> ZFS?
>>> vinum? gmirror? Can I expect them to work better with ahd given ahd
>>> cannot
>>> handle pulling of working drives out of SAF-TE aware enclosure?
>> We're pretty sure it's not the /RAID Software/ and that it's a driver
>> issue. I don't think with your version of FreeBSD that you can do *any*
>> hot swapping of drives with that controller.
>> Ask the maintainer of the ahd driver to take a look -- he might be able to
>> provide a patch.
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