Subject: Re: Software RAID-0 performance
To: None <firstname.lastname@example.org>
From: Charles M. Hannum <email@example.com>
Date: 07/03/2004 00:44:56
On Saturday 03 July 2004 01:42, firstname.lastname@example.org wrote:
> Charles M. Hannum wrote:
> >On Saturday 03 July 2004 01:28, email@example.com 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?