External SCSI CDROM

[Ron Grove_1]

Hello,

I just picked up a C110 recently so that I can learn HP-UX much more thoroughly (read in so that I can break it badly and not have anyone shouting at me...), but it doesn't have a CDROM installed. I've not dealt a great deal with SCSI hardware before so it is somewhat new to me. I do have an older Sun 411 external CDROM, but it has a "normal" SCSI interface and the spec sheet for the C110 says it has a Fast/Wide SCSI 2 interface. Do I have any hope of getting these guys to communicate or should I just start looking for another external SCSI CDROM?

Thanks,
Ron

[Pat Copland · Accepted solution]

SCSI is well known as being backwards compatible. You should just need to order/locate a 50 pin to 68 pin adapter (I recently had to do this with an old tape drive mounted in a new SCO box). The only down side is that you may be stuck with the
lowest common demoninator as far as performance of other devices on the bus. Seeing as this unit is to be used out of production, this should not be a problem to you. I would borrow an adapter, hook it up and see if you like it.

[Bill Hassell]

SCSI compatibility? An oxymoron perhaps. Actually, a large number of HP workstations were sold with Fast/Wide Differential, a SCSI standard that is electrically incompatible with any other form of SCSI. Make sure te label does not say the word differential or use the abbreviation FWD. If it does, you cannot use any CDROM that is not Fast/Wide/Differential.

As far as the Sun CDROM, it will probably work online but won't be of any use for cold installs or booting. HP-UX hardware requires a different sector size on CDROMs in order to boot. Only the Toshiba brands and most Plexstor drives will work for booting and installs without HP-UX running. Once booted, most SCSI CDROM drives work OK.

[Claus Nymann]

Hi Ron,

It should not be a problem to make it work. The C110 features 2 scsi channels. (And 2 external connectors). There is a connector labeled "fast wide scsi" (68 pins) - this is a Fast Wide differential controller (16bit 10Mhz = 20MB/s). Now the key is here is "differential". Your CDROM-drive is most likely "single ended" and thus incompatible with differential controllers. Do not attach your CDrom drive to this connector - you may damage both units.

The C110 also features a "narrow fast scsi2 single ended" controller. That is the connector labeled "single ended" (50 pins). This is the one to go for. Get the right cable (50HD-50LD, I guess) and a terminator and you should be able to get it working as long as you remember to add the "cdfs" driver to the kernel (use SAM). One point here - you are likely to fail if you try to install from scratch using a non-HP cdrom - booting from CD is only a job for HP-labeled cdrom-drives.

[Ron Grove_1]

Thank you all of this information. I do want to learn how to install HP-UX 11.0 from scratch so a 100% compatible CDROM is very important to me. Can someone point me in the direction of someplace that has CDROM's that are definitely bootable and will install HP-UX? I'll continue to poke around, but the I havent found a wealth of HP-UX information out there yet. I imagine I just haven't turned over the right rocks yet...

[James R. Ferguson]

Ron:

Funny you should ask...just today there was a post with two responses that should certainly start you off! That's the good news. See:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,1150,0x7af16c96588ad4118fef0090279cd0f9,00.html

...and the bad news...

I think you will need some sort of support contract to be able to obtain the CDROMs of software, however. You should contact HP to see what you can arrange. For more information and maybe a vehicle to start that process, click on the ASSISTANCE button to your left on this forum.

Hopefully this helps. Good Luck!

...JRF...