Re: Possibility for a parallel relaxed RAID?

Neil,

How does md make the decision to drop a drive from the array? Is it a
fail message back from the ATA layer? Quickly getting over my head
here, but I would like to think there are different types of failures
and a failure to complete error correction on the drive should not be
a fatal error to md.

This request is the same as the post I have made earlier this week
regarding "RAID class" drives which I would love to get your response
to.

Tks

On Thu, Mar 18, 2010 at 3:54 PM, Neil Brown [off-list ref] wrote:

On Thu, 18 Mar 2010 15:01:44 -0400
Berkey B Walker [off-list ref] wrote:

quoted

There maybe many folks out there who want to use RAID on their personal,
non-production systems.  Assuming access and thru-put values are not
critical a problem might be "You can't use Desktop drives for RAID".
Which, I think, most of us know is not really true, but - - If the
timing issues were to be relaxed, allowing the drive to fix itself,
before being kicked by the md process, might not the average Joe be
better served?  There is a big difference between going a mile and
buying a commodity drive, and being "up" in an hour vs. finding a
working system, going online, paying price+, and getting/paying fast
shipping. Which might resolve the issue in days instead of hours.

Any possibility of a parallel, less critical to drive response, release
of md?  Or a patch to allow same?

This is not a function of 'md'.  md has no timeouts for drives responding.
It just submits a request and waits for a success/fail reply.

It may be a function of the lower level SATA/SCSI/FC/whatever driver.  You
would do better to ask the developers of those drivers, maybe start with the
maintainer of libata.

NeilBrown
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