Hi,
Forget that. I'm an idiot.
Raid1 is mirroring, Raid0 is striping.
Sorry for the screw up.
- David Harris
Principal Engineer, DRH Internet Services
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of David Harris
Sent: Saturday, December 26, 1998 12:53 PM
To: Eyal Lebedinsky; [EMAIL PROTECTED]
Subject: RE: software raid chunk size
Hi,
Eyal Lebedinsky wrote:
> I am now studying the RAID implementation. For starters I attached some
> discarded sun disks (6x200MB QUANTUM Model: PD210S SUN0207 Rev: 492S)
> and set to measure the results. the disks seem to be slow on their own
> (hdparm says 1.36 MB/sec) and I expected some speedup when striped
> (raid0). I got 2.8 MB/sec, just over twice the speed. What gives? I use an
> ASUS SC200 SCSI controller, Narrow SCSI, on 2.1.132 with the latest
> raid patch and tools.
You mention that you are trying to achieve a read speed boost from
"striping", but then mentioned that you are running raid0. Your problem here
might be that raid0 is not striping, but rather mirroring. It is true that
mkraid requires a chunk-size for raid0, but this is not used for any
striping. That chunk-size is there just to pacify the internal mechanics of
the driver. I recommend specifying 128k.
For a description of the different raid levels, see:
http://linas.org/linux/Software-RAID/Software-RAID-2.html
But ignore that raid-HOWTO when it talks about the specifics of the drivers,
because it was written for a completely different earlier version.
- David Harris
Principal Engineer, DRH Internet Services
