RE: Dying disk and filesystem choice.

["Cress, Andrew R" <andrew.r.cress@intel.com>]

>At 12:19 PM +0200 2001-05-24, Jens Axboe wrote:
>>In fact you will typically only see an I/O error if the drive _can't_
>>remap the sector anymore, because it has run out. No point in reporting
>>a condition that was recovered.
>>
>>I'd still say, that if you get bad block errors reported from your disk
>>it's long overdue for replacement.

On Thursday, May 24, 2001 11:46 AM, Jonathan Lundell wrote:
>This can't be right. It implies that the drive is returning bogus 
>data with no error indication. Remapping a bad sector is not the same 
>as recovering it.

The automatic reallocation of bad spots on a drive is safe unless paired
with the write cache enabled bit in the disk mode pages (configuration).
WCE, in some cases, can cause the write/read to both take place from cache
with good status, and if the bad spot is reallocated later, when the cache
is flushed, the reporting gets very confusing.

In general:
It is a common misconception that if a disk begins to show some bad spots,
that it should be replaced.  In fact, a disk can have a reliable, useful
life for years after bad spots begin to show up.  The number of bad spots in
the Grown Defect List over a specified time as a % of capacity can be an
predictor of impending failure, however.

Andy Cress