Subject: Re: Many PCI IDE cards in one box, is this possible?
To: Brian Buhrow <>
From: Thor Lancelot Simon <>
List: current-users
Date: 01/19/2001 10:56:27
On Fri, Jan 19, 2001 at 05:56:34AM -0800, Brian Buhrow wrote:
> 	Actually, I put 11 drives in a single raid 5 array, and 
> made the 12th drive a hot spare.  The parity calculation seems to take
> about
> 24 hours, and while it's running, it takes a half hour to login.  This is

That's because your drives are all in PIO mode, chewing up CPU for each
and every single access.

You need to figure out why they aren't using DMA mode (but with that many
drives, multibyte DMA probably isn't safe -- you need to use UDMA since
you really want the data checksum it does).

You probably have a cabling issue.  How on earth did you get all 12 drives
into one chassis while meeting the 18" cable length restriction?  Are you
using UDMA-66 cables (one end blue)?  You need to.