Re: IIs factible to implement full writes of strips to raid using NVRAM memory in LFS?

[Jose Luis Rodriguez Garcia <joseyluis%gmail.com@localhost>]

On Mon, Aug 22, 2016 at 5:12 PM, Greg Oster <oster%netbsd.org@localhost> wrote:
...
> RAIDframe maintains a 'Parity status:', which indicates whether or not
> all the parity is up-to-date.  Jed Davis did the GSoC work to add the
> 'parity map' stuff which significantly reduces the amount of effort
> needed to ensure the parity is up-to-date after a crash.  (Basically
> RAIDframe checks (and corrects) any parity blocks in any modified
> regions of the RAID set.)
>
As I understand, parity + parity status, only resolves in a efficient way the
problem of write hole of RAID 1/rebuilding the parity, although it can
have a small penalty
in performance or time for rebuild the parity in busy storage, that
usually are critical servers.

For RAID-5/6 The problem of write hole continues (it is only resolved
if it only affects the parity).