Subject: Re: setting the clean-bit in a RAID 0
To: Greg Oster <email@example.com>
From: Frederick Bruckman <firstname.lastname@example.org>
Date: 04/07/1999 12:16:39
On Wed, 7 Apr 1999, Greg Oster wrote:
> Paul B Dokas writes:
> > caligula# raidctl -i raid0
> > Initiating re-write of parity
> > raidctl: ioctl (RAIDFRAME_REWRITEPARITY) failed: Invalid argument
> > I've done this before. It makes to difference. The clean bits have
> > not been set.
> Doing the above will now succeed trivially, and will set the clean bit for
> RAID 0. It's not the worlds most elegant solution, but it'll certainly
> suffice until I get a chance to revisit the issue...
It's reasonable to want to use the clean bits to script recovery after
a power failure. I can think of at least three ways to do this. 1)
Parse the output of `raidctl -c' with sed. 2) Have `raidctl -c' return
a distinct value if the underlying partitions aren't clean, whether
actually mounting or not, or 3) Have another switch that does no more
than check parity, or rebuilds it only if necessary. (OK, that's 5.)
I do think it's important to at least have a fighting chance of coming
up gracefully if the power is simply cycled, but the old way of
rebuilding parity on every boot is way too slow. Any thoughts on this?