On 2015-08-11 00:59, Chris Murphy wrote:
On Mon, Aug 10, 2015 at 12:46 PM, Carlos E. R. <> wrote:
But that damage should not be permanent, I suppose. Writing that sector with data should correct it, right?
Transient vs persistent error is determined when the sector is written. If the verify of write succeeds, case closed. If it's transient there's a limit to how many errors are permitted (varies), and if it's persistent it causes that physical sector to be removed, and the LBA to be remapped to a reserve sector where the data is written (verified and succeeds). If there are no reserve sectors remaining, that causes a write error. Different file systems have different ways of dealing with that case, whether a bad sector map is supported or not (recent versions of mdadm do, ext234 has long had such support, XFS and Btrfs do not).
IIRC, initially reiserfs did not, and support was added later. At the time, I think disks did no remapping, or we did not know about it, so it was a problem if the filesystem could not cope with bad sectors. -- Cheers / Saludos, Carlos E. R. (from 13.1 x86_64 "Bottle" at Telcontar)