unreadable sectors, what to do?

[Dave Ihnat]

On Fri, Oct 12, 2007 at 01:46:56PM +1000, Cameron Simpson wrote:
> You're still at risk of course, but since I don't believe that bad
> sectors spread like a fungus I suspect you're not at much more risk than
> you already are with RAID0.

Ahh...that may not be quite right.  If the bad blocks are just due to
a failure in the oxide coating _in situ_, maybe.  But I've seen cases
where the failure actually resulted from some of the oxide flaking
off--head strikes, most commonly--and this *can* "spread like a fungus"
as the particulate can damage heads, stick to platter surfaces and cause
further damage, etc.

Reflecting, I don't think I've seen that kind of failure since drives
have been using cobalt oxides, but nevertheless, hard as it may be, it's
still a coating.  The general rule still applies--once you start seeing
failures on your side of the interface, it means you've been undergoing
enough failures that the on- drive sector remapping is exhausted;
you've already experiencing multiple sector failures for some time.
It's time to change drives.

Cheers,
--
	Dave Ihnat
	President, DMINET Consulting, Inc.
	dihnat at dminet.com