Re: hardware recovery and RAID5 services

[Roger Heflin <rogerheflin@gmail.com>]

And do not do write-sector on a disk that is in use in RAID, otherwise
that sectors data is gone.

I will completely remove a disk/partition and do --write-sectors
against it and then do a --add (don't do a re-add).    In general
though I have not had a lot of luck with the write-sector fixing
and/or forcing a reallocate even when the sector is clearly bad.  I
have to conclude (based on both WD and seagate not reallocating
sectors that reliably fail rereads in <30-seconds after just being
re-written) that pretty much everyone's disk firmware must suck.

Would --make-bad-sector work to force a reallocate?

On Mon, Jan 31, 2022 at 9:40 AM Nix <nix@esperi.org.uk> wrote:
>
> On 29 Jan 2022, Wols Lists told this:
>
> > I believe there is also a way of injecting a hardware error onto a
> > drive. Unless you can take a backup of the backup :-) I wouldn't
> > recommend it at the moment, but there's some ATA command or whatever
> > that tells the drive to flag a sector as bad, and return a read error
> > until it's over-written.
>
> See hdparm --make-bad-sector. The manpage says "EXCEPTIONALLY DANGEROUS.
> DO NOT USE THIS OPTION!!". It is not lying. :)
>
> (This is also --write-sector, which is merely VERY DANGEROUS, but can be
> used to force rewrites of bad sectors. Make sure you get the sector
> number right! Needless to say, if you don't, it's too late, and there's
> no real way to test in advance...)