Subject: Re: comparing raid-like filesystems
To: Antti Kantee <>
From: Jukka Marin <>
List: current-users
Date: 02/03/2003 09:45:00
On Sat, Feb 01, 2003 at 11:08:32AM +0200, Antti Kantee wrote:
> On Sat Feb 01 2003 at 10:04:25 +0200, Jukka Marin wrote:
> > I have no experience of the RAID controllers, but I'm not particularly
> > happy with the NetBSD RAIDframe implementation.  I bought fast disks,
> > configured RAID - and found out that RAID drops the performance to a
> > fraction of that of the disks.
> > 
> > I don't know why, because when RAID is 100% busy, CPU load is almost
> > zero and the disk load 25% or so.  It's like if RAIDframe had some
> > usleep() calls in the code to make things go slower..
> What's your stripe unit size? I also was suffering from inexplainable
> slowness until I dropped the stripe unit size to 16 sectors. Before that
> my RAID5 gave something like 5MB/s write speeds, now it's giving more
> than 25MB/s.

Does this apply to RAID1 as well?

I understand that software RAID is slower than the disks (although with
the CPU's of today...) but I do NOT understand why RAID is 100% busy
when none of the resources of the server (CPU, disks, memory) is.  I see
this on my server and a friend sees it on his.