Re: Linux 2.6.3-rc3 - IDE DMA errors on Thinkpad A30

Jeff Garzik
2004-02-16T03:47:54Z

Chip Salzenberg wrote:
> Still: I wonder if the occasional bad sector is really that bad.
> Shirley, at the unreal densities of today's drives, the development of
> bad sectors is inevitable? (Especially in a laptop drive that's
> bounced around in normal use.)

Open argument :)

A lot of smart people will argue that a bad sector every now and again
occurs, and "I've run my server's disks that way for years."

Other equally smart people argue that modern IDE disks reserve space for
remapping bad sectors. If you run out of sectors that the drive is
willing to silently remap for you, you should toss the disk and buy a
new one.

There is of course the caveat that it is impossible to avoid the drive
returning "bad sector", instead of silently remapping, on reads.

Oh, and I just thought of something else. Current Linux filesystems
will, on a read error, usually mark it as a bad sector and move on.
Really, they should attempt to write to the bad sector before
considering it bad.

As a result, current kernels will AFAICT assume a sector is bad even
when the drive politely swaps a good sector in place for you.

One for the todo list, I suppose... a useable workaround for this is
probably good ole 'e2fsck -c', i.e. badblocks... That says "check again
to see if this sector is bad", and -hopefully- will unmark bad blocks
that were incorrectly marked bad.

Jeff