[rescue] Small RAID array setup

Robert Novak rnovak at indyramp.com
Mon Jun 30 14:39:51 CDT 2003

On Mon, 30 Jun 2003, Charles Shannon Hendrix wrote:

> On Mon, Jun 30, 2003 at 01:05:16AM -0700, Robert Novak wrote:
> > CMD controllers are also available in various forms. Search ebay for "cmd
> > raid" ... there's a CRD-5500 up there now that's currently at $10 with
> > 2d10h to go... 8 single-ended drive channels going to one wide
> > single-ended host channel. That's pretty cheap. It's hardware raid. And it
> > should work with the Classic's scsi ports (onboard or sbus) with
> > appropriate cabling.
> It seems to be a box full of SCSI controllers... and the heading says
> they are all 8-bit channels.
> Is the listing incorrect, or is this a version for running 8 narrow SCSI
> drives?

It's for running 8 narrow scsi channels. So max of 56 drives.

> With this unit, then you still seem to need another cabinet for the
> drives.

Generally it's in a multibay chassis with the drives. The unit is a
full-height drive space, like an older 8mm tape drive, and the "host"
controller goes to your host; the "drive" controllers go to your drives.

> I'd like something like this, but with the drives and controller in a
> single unit, that appears to my host as a SCSI chain.

Appears as a scsi chain or a scsi device? The external hardware raid
devices tend to represent all connected devices as a single scsi device
which may have multiple LUNs.

I used CMD-based products from Zzyzx at a previous employer. You configure
the raid unit to export whatever LUNs you want, and then the host sees
those luns as parts of a single disk. You format/partition the lun, make a
filesystem, and mount it. The host doesn't care whether the lun is a
single disk or a thousand disks. It can't see the components, just the
virtual disk (and it doesn't know it's virtual, unless it understands the
SCSI ident string).


Robert Novak - rnovak at indyramp.com

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