[BBLISA] RE: storevault / netapp

[Edward Ned Harvey]

> RAID can be implemented in hardware or software. Can't speak to all
> hardware
> RAID controllers, but NetApp does RAIDDP, and ZFS has RAIDZ2, both of
> which
> are double-parity-disk RAID (i.e. Survive 2 disk failures rather than
> 1).

This is very interesting.  Is there any hardware controller that does the
same?

I do think there's value in the hardware raid controller.  Guess what, we've
all seen sometimes kernel crashes.  And if we had enabled write caching,
we'd encounter FS corruption for whatever had not yet been written.  But
with a caching raid card, with battery backup, you get all the performance
benefit (if not more) with lower risk of data corruption.

The performance difference is most apparent when working on a zillion small
files.  The most dramatic difference I've seen is when formatting the FS,
because of course, that's such a sparse write operation.  To format 1Tb on
my Dell, ext3, it took 40 minutes without write cache enabled on the raid
card, and it took 40 seconds with the write cache enabled.