Re: Soft Raid5 Problems
Hi,
Please note that with some disks, formatting may not do anything, or do very
little. I was dismayed to buy a 40 MB IDE drive recently and then download the
formatting utility, only to find that it formatted in under 5 seconds.
What I suggest you do is find some software that will do a bad block check and
save the list of bad blocks into a file. FWB hard drive toolkit for the Mac OS
does this, I'm sure there is something for Linux that does but I'm not sure what
will. You will want to do both a write and read test - some bad block tests
only read from the disk so they don't risk corrupting it.
What you do is repeatedly run the bad block checks to see if you get new bad
blocks with each test.
If you're really strapped for cash you can keep doing this until no more bad
blocks show up and then use the disk with all those bad blocks mapped out. But
if the bad blocks never stop coming you've got a bad disk. Note that it might
be the controller on the drive, the media on the disk, the IDE or SCSI host bus
adapter, or your cable - one cheap thing to try is switching the cable with a
known good one.
I was in such a jam once, dead broke and facing a deadline when a five year old
SCSI disk on my mac went south on me. I repeatedly reformatted and bad block
tested it for about three days before it settled down, after which I was able to
continue using it. The drive is about 7 years old now and except for that one
event it is still working. I think it was damaged by heat from using a poor
external SCSI housing.
I believe SCSI disks have a bad block mapping table built into the drive so you
can just keep testing it until no more show up and it should work. I'm not sure
about IDE drives but I suspect they don't, which is maybe why the filesystem
formatters do their own bad block checking.
Michael D. Crawford
GoingWare Inc. - Expert Software Development and Consulting
http://www.goingware.com/
crawford@goingware.com
Tilting at Windmills for a Better Tomorrow.
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