Re: when does it become faulty disk

[raz ben jehuda <razb@bitband.com>]

thank you molle.
This was a very helpful information.
On Mon, 2005-06-20 at 10:55, Molle Bestefich wrote:
> raz ben jehuda wrote:
> > So, what about write errors ?
> > from what you are saying i understand that when a write error occurs
> > the disk is faulty.
> 
> Yes..  If you are serious about your data redundancy, yes.
> 
> A sector _read_ error is a notification from the disk that a sector
> has gone bad and that some particular data is lost.
> 
> A sector _write_ error is the disk telling you that:
>  1. The sector has gone bad.
>  2. The disk failed to relocate the sector to the spare area, probably
> because it's full.
> 
> The above are slight simplifications, since other kinds of read and
> write errors may in very rare cases occur.  That's OK though, since
> you DO want sick disks with strange internal errors that are causing
> read or write errors to get kicked.
> 
> In rare cases a disk could get sick in a way where writes to a bad
> sector succeeds but subsequent reads fail.  Never seen it happen...
> But just in case, you might want to re-read a failed sector after you
> have written to it, just to check that the disk actually correctly
> relocated it.
> 
> Once a disk has been kicked, you may want to instruct the user to
> check that the disk's spare sector count has indeed reached 0, by
> using smartctl -a /dev/xxx.  That command will also tell of other disk
> failures.
-- 
Raz
Long Live The Penguin