[rescue] Re: Re: Re: OSM-2000/RSM214

[Jonathan C. Patschke]

On Thu, 18 Apr 2002, Joshua D Boyd wrote:

> So, does this mean that I shouldn't buy the UltraWideDiff sbus card I
> see at a great price, and instead pay the same amount of money for a
> FastWideDiff card?

The label on mine reads "WARNING: Do not connect this device to a host
adapter which operates at Ultra-SCSI (40 MB/s) speeds.  Although it will
operate at these speeds, data integrity cannot be ensured."  I never tried
connecting it to an Ultra-SCSI adapter.  My experience was going from a
SPARC 10, through a DEC Storageworks bus converter into the shelf.

If the built-in Unisys bus converter can't keep up with an UltraSCSI
signalling rate, the result will probably be the same (signal skew,
failure under load, generally crapping out).

Here's what I'd recommend.  If you don't have a differential card in your
system, sell the shelf, and pick up a Sun 711 Multipack.  Same idea as the
shelf, only better drive density (if you use Ultrawide 1-inch discs) an no
silly bus conversions or other useless logic getting between your host
adapter and your discs.

If you're dead-set on using the shelf, get the FWD card instead of the
UWD.

> Sigh.  This shelf had better perform really well because it is
> certainly going to cost me enough to get it going.

It's going to perform just as well as any seven discs on a relatively
short SCSI chain will.  It's -just- a shelf, no different than plopping
seven disks in a minitower enclosure.  To do anything fancy, you need the
control module.  That's when it really becomes worth it, as you get
hardware RAID and realtime monitoring.

That being said, if you populate it with decent discs, you probably won't
be disappointed.

--Jonathan