I wanted to follow-up that with kernel 2.3.51 I get raid0
performance problems similar to those reported below, but at larger file
sizes.
I created files of approx. size 256 MB, 512 MB, and 1 GB. I did simple
tests 'time cat file ... > /dev/null' on different file sizes/counts,
always totalling 1 GB of data. the real time for one 512 MB file is
about 15 seconds, and for two 512 MB files is about 30 seconds.
however, the real time for one 1 GB file is about 65 seconds.
this is on a dual 550 MHz PIII with 256MB RAM, two SCSI disks with
a 48 GB partition on each disk, raid0 w/ 256 KB chunk size, and an
ext2 filesystem. the SCSI adapter is Adaptec AIC-7896/7 Ultra2.
karl
> Date: Fri, 3 Mar 2000 19:58:26 -0500
> From: James Manning <[EMAIL PROTECTED]>
> Subject: Re: kernel 2.3.4X raid0 performance problems
> [ Friday, March 3, 2000 ] Karl Czajkowski wrote:
> > I upgraded the kernel to 2.3.47, 48, and 49 and got a performance
> > problem where "time cat file ... > /dev/null" for a 300 MB file shows
> > some scaling, but for a 600 MB file the throughput is almost identical to
> > a single disk.
>
> how much memory in the machine?
>
> > is there a known scheduling problem with the 2.3.4X kernel raid vs. the
> > 2.2.12-20 patches distributed by redhat? I need the new kernel for
> > ethernet patches...
>
> 2.3.4x raid merge isn't finished yet, but I'm surprised raid0 not
> working as well as it sounds like it should.
>
> > I also noticed that the "boot with raid" option in the kernel won't compile
> > properly in the 2.3.4X series.
>
> should once merge is finished.
>
> James
>
