Disk reliability (Was: Node cloning)

[Greg Lindahl]

> For IBM drives (IDE or SCSI), one can download and use the Drive Fitness
> Test utility (see
> http://www.storage.ibm.com/techsup/hddtech/welcome.htm).  This program
> can diagnose typical problems with hard drives.  In many cases, bad
> blocks can be 'healed' by erasing the drive using this utility (back up
> your data first, and be prepared for the 'Erase Disk' to take an hour or
> more).  If that fails and your drive is under warranty, the drive ought
> to be replaced.

NOOOOOOOOOOOOOOOOO!

If a sector returns the wrong result 0.01% of the time, it is bad, but
testing is unlikely to be intensive enough to detect it (10,000
reads...) If you "heal" it, it will appear to work at first, but it
will eventually turn up bad again. So all you're doing is papering
over the problem. You ought to just replace the disk.

-- g