Re: SCSI port type

[Dan Oglesby <danno%serverunderground.com@localhost>]

----- Original Message -----
> From: "Volker A. Brandt" <vab%bb-c.de@localhost>
> To: "AGC" <agcarver+netbsd%acarver.net@localhost>
> Cc: port-sparc%NetBSD.org@localhost
> Sent: Sunday, December 16, 2012 9:39:01 AM
> Subject: Re: SCSI port type
> 
> > > Alexander Carver writes:
> > >> Ok, then I'll just have to track down an LVD S-bus card, that
> > >> should get interesting.
> > >
> > > No need.  If you are talking about the Multipack 2 (i.e. the 6
> > > bay
> > > version), well, it says UltraSCSI on the front, and that's what
> > > it
> > > is.  :-)
> >  > All disks you put in will clock down to UltraSCSI (== FastSCSI
> >  > 20).  You can then use any SE SBus SCSI card.  There never were
> >  > any SE UltraSCSI SBus cards, at least from Sun, but they had SE
> >  > "Fast Wide", which should also work as it is only a difference
> >  > of
> >  > speed.  The Multipack will clock down appropriately.
> > 
> > Two of the Multipacks are 6 bay and one is the 12 bay.  The drives
> > that I have to install in them are all low voltage which is why I
> > need the low voltage card to run them (I've got 18 146GB LVD SCA
> > drives waiting to go in them).
> 
> No, you don't.  The key is the connection between the card and the
> multipack, which is UltraSCSI.  So you can use any SE card.
> 
> The drives will work in the multipack because a LVD device will fall
> back to SE if you plug it into an SE bus such as the multipack
> backplane.
> 
> > > There are nice SBus cards with an extra hme and "Fast Wide" SCSI
> > > (X1018A, 501-2739).  :-)
> > 
> > I've seen that card but I can never seem to find any documentation
> > that would tell me if it was a low voltage or a high voltage card.
> 
> Neither.  It is SE.
> 
> 

This is a general reply to the conversation.  I am in agreement with Mr. Brandt.

LVD hardware is backwards compatible with SE.  I have used onboard SE 
controllers on SPARC workstations (SS2, SS5, SS20) to drive newer LVD style 
drives in the past.

HVD hardware won't talk to SE or LVD hardware.  I have an LTO tape library that 
is HVD for the enclosure and the drive, and had to figure out what I needed to 
drive this beast years ago when all I had was SE and LVD equipment.

"Most LVD devices are "multimode", automatically detecting when they are 
attached to a single-ended bus, and operating in single-ended mode. This makes 
it possible to mix LVD and single-ended devices on the same bus. However, if 
only one single-ended device is connected to a SCSI bus, all devices on that 
bus will operate in single-ended mode, and all of the single-ended limitations 
will apply: shorter cable lengths, fewer devices, and slower bus speeds."

http://support.tandbergdata.com/knowledge-base/display.cfm?id=775

--Dan