Re: WAPBL

[Thor Lancelot Simon <tls%rek.tjls.com@localhost>]

On Thu, Jul 31, 2008 at 09:48:00PM +0100, Matthias Scheler wrote:
> 
> Any brilliant ideas how to teach RAIDframe (ETA for parity rewrite
> is 1:28 hours) to perform only limited parity rewrites after a crash?

I think the parity logging code could be enhanced to do this (in addition
to providing the significant performance benefit it should already provide).
It divides the volume into "parity regions" already, so it should be possible
to add a clean bit per parity region, set after each parity log transaction
completes.

Greg says the parity log code has some problems with large disks -- it
doesn't use large enough regions (they seem to be fixed size), so it
wants e.g. 1GB of kernel memory per 1TB of managed disk.  But that could
presumably be addressed.

I am *not* volunteering to do this.

-- 
Thor Lancelot Simon                                        
tls%rek.tjls.com@localhost
 "My guess is that the minimal training typically provided would only
 have given the party in question multiple new and elaborate ways to do
 something incomprehensibly stupid and dangerous."      -Rich Goldstone