Subject: Re: Software RAID-0 performance
To: None <>
From: Charles M. Hannum <>
List: netbsd-users
Date: 07/03/2004 00:44:56
On Saturday 03 July 2004 01:42, wrote:
> Charles M. Hannum wrote:
> >On Saturday 03 July 2004 01:28, wrote:
> >>I've been trying to measure NetBSD software RAID-0 performance on my
> >>system, with 2 hard disks arranged for striping, however the numbers
> >>(bandwidth) don't seem to add up, i.e.
> >
> >There are a number of problems here.  The biggest one is that dd(1)ing
> > from the "raw" device does not do any read-ahead.  That is to say, it's
> > completely synchronous, and so it may not keep all the subunits busy.
> Well reading from a block device makes it even worse:

"Block" devices are sort of a sad joke that should probably be removed.  How 
about trying it with a file in an actual file system, and say bs=32k?