Re: FC4 kernel performance

[Chris Adams <cmadams hiwaay net>]

Once upon a time, Gregory Maxwell <gmaxwell gmail com> said:
> This isn't completely true. As it stands linux raid currently lowers
> the reliability of the system. This is because a single bad sector
> will take a drive offline. In the process of trying to resync the
> offlined drive, the other drive(s) will encounter a bad sector and
> come offline. You end up with the entire array down.

Just FYI: this is not a problem exclusive to Linux software RAID.  I
have seen similar behavior out of LSI MegaRAID cards as well (and I
think other hardware RAID controllers work in a similar fashion).

Most things consider a bad sector a sign of a bad drive.  On today's
drives, where bad sectors are remapped internally to the drive, by the
time you see a bad sector, the drive has remapped a bunch of sectors
(and may be out of spare space).

Some type of "journalling RAID" would be a possible solution (and would
also allow for much faster re-syncs on unclean shutdown, as only the
last written blocks would need updating).
-- 
Chris Adams <cmadams hiwaay net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.