Re: Are linux-fs's drive-fault-tolerant by concept?

["Dr. David Alan Gilbert" <gilbertd@treblig.org>]

Hi,
  Besides the problem that most drive manufacturers now seem to use
cheese as the data storage surface, I think there are some other
problems:

  1) I don't trust drive firmware.
	2) I don't think all drives are set to remap sectors by default.
	3) I don't believe that all drivers recover neatly from a drive error.
	4) It is OK saying return the drive and get a new one - but many of
	   us can't do this in a commercial environment where the contents of
		 the drive are confidential - leading to stacks of dead drives
		 (often many inside their now short warranty periods).
		 
To be fair I'm not sure if it is only the drive firmware I don't trust -
it could be the controllers and the IDE drivers as well - I don't know.

While RAID works well for drives that just go pop and die, for drives
with dodgy firmware we just sit there and watch the filesystems decay.
I don't think the kernel can do much about that - but it is a sad state.

I'd find two things useful in this respect:
  1) A tool to check the consistency of a RAID - presuming I shut my
	RAID down safely I should actually be able to use the redundant
	information to test it; this should reveal corruption early.
	(Perhaps the kernel could check a few sectors a second in the
	background)

	2) A disc exerciser - something that I can use to see if this drive,
	connected to this controller, on this motherboard on this kernel
	actually works and keeps its data safe before I put it into live
	service.

Dave (After a few weeks of fighting pissy IDE hard drives)

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