Subject: Re: IDE bad sector remapping vs. write-cache
To: Daniel Carosone <email@example.com>
From: walt <firstname.lastname@example.org>
Date: 08/17/2003 11:43:43
Daniel Carosone wrote:
> Modern disks are supposed to automatically remap bad sectors when
> an error occurs...
> However, it seems that (some?) IDE disks may not do bad sector
> remapping on write if their write-cache is enabled...
> Does anyone have any knowledge to add? ...
Knowlege is too optimistic for what I have, but here it is FWIW:
I have an older WDC WD450AA which has gone bad on three different
occasions and recovered each time -- but very slowly.
Each time the disk remained bad for weeks or months -- it was
only a secondary disk so I was too lazy to yank it.
I've concluded after three episodes that turning the power off
was the event that triggered the recovery. Powering the machine
off is something I almost never do, which is why the disk stayed
bad for so long each time, I think.
The third failure even produced a scary "SMART status BAD" error
message from the BIOS when rebooting the machine. I assumed that
the disk had finally used up all the available sectors for re-
mapping and that was that.
BUT, the next time I powered the machine down overnight the BIOS
reported the SMART status was OK again. I was amazed. The disk
is still feeling solid right now, so I'm once again not tossing it.
In fact, this installation of NetBSD-current is running from that
disk. (But it's just a play machine.)