Re: Pathological RAIDframe rebuild times

[Chuck Swiger <cswiger%mac.com@localhost>]

On Apr 8, 2011, at 3:33 AM, Stephen Borrill wrote:
> I've a couple of HP Microservers, both with 4x WD Caviar Green 2TB drives. 
> Operating system (netbsd-5) is on USB (same image used on both). Drive write 
> caches are enabled in the BIOS and also double-checked with dkctl.

The WD Green drives have firmware which has a very short timer before it 
unloads the heads and tries to spin down to save power.  They're not intended 
for use with RAID configs, although they probably won't break RAID-0 or RAID-1 
due to missing TLER.

The first issue you might be able to tweak with a utility floating around 
called wdidle3.  However, if you're running a RAID-5/6/10 config, please 
understand that the drives you've got are not intended for the role, and you 
will encounter performance issues and possibly even data corruption if more 
than one drive goes into a deep recovery cycle and gets marked offline from the 
RAID array.

Regards,
-- 
-Chuck