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HP DAT72 and disks on same bus on a PWS

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Bengt Nilsson_2
Regular Advisor

HP DAT72 and disks on same bus on a PWS

I have severe difficulties on a PWS433 (or a PWS500, same behaviour ) to have disks and a HP DAT72 tape device on the same SCSI bus, the disks come and go at random or no devices show up at all, including the tape.

Is this a know problem?
Any remedy except having a extra SCSI interface dedicated to the tape?


17 REPLIES
Steven Schweda
Honored Contributor

Re: HP DAT72 and disks on same bus on a PWS

Shorter cables? Proper termination? Where
are all these devices? Internal? External?
With single-ended SCSI, it's difficult to
have both on one adapter without exceeding
the maximum cable length (which can be
remarkably short).

On my main XP1000, internally I have two hard
disks and a DVD-ROM drive on the on-board
SCSI, and externally, a tape (DLT), a hard
disk, and a CD-R/RW drive on a KZPBA-CX card
(which has nothing connected internally).

You may not need a SCSI card dedicated to the
tape, but you may need one (or more) cards
dedicated to external devices.
Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

The problem is internal or external, short or long cables (how long is short/long? I have an internal cable about 40 cm long), with and without termination, anything you would suggest.
Right now I have it connected to an extra scsi card, and it works. The only painful thing is the PCI scsi external connector, that is useless since if I connect anything to it, the tape stops working and the connected device is never detected if I do. So I will have to tape it over with red tape.


Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

I have got a hunch that the problem may be that of HVD / LVD / SE bus compatibility.

The HP DAT72 is a LVD/SE device, the specs says.

What kind of bus do we have in a PWS500? HVD or LVD?


Steven Schweda
Honored Contributor

Re: HP DAT72 and disks on same bus on a PWS

> [...] (how long is short/long? [...]

40cm should be short enough. A Web search
for keywords like "scsi cable length" should
find some opinions/facts. External cables
tend to be longer than they look because of
the cable hidden inside drive enclosures.

> [...] with and without termination [...]

Where is "with"? Some devices have built-in
terminators which may need to be disabled.
You should have only one terminator at each
("terminal") end of the cable.

> What kind of bus do we have in a PWS500?
> HVD or LVD?

SE, normally. LVD devices should be able to
adapt to single-ended environment, however.
(Most of my hard disks are LVD/SE, for
example.)
Rob Leadbeater
Honored Contributor

Re: HP DAT72 and disks on same bus on a PWS

Hi,

This sounds to me, almost certainly a termination issue. As Steven suggested, you may have something double terminated, especially if you're trying to use, both internal and external connectors of a SCSI card.

Cheers,

Rob
Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

"Both" meant of course not double termination, just that I tried both with a terminated cable, as well as a cable with terminator. None worked.

Now, I got some success.
I saw on the HD that there was a strap "force single-ended mode". I put a strap on it and then it actually seemed to work. However it has been working now and then before, so time will tell.

Seems like mixing old and new devices may cause problems.
Again, what mode is most probably used by the QLogic and on-board controllers in a PWS500?
Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

Sorry, I missed that you already answered the SE/LVD question.

Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

My conclusions were too fast. "Force single sided" did not do the trick. The tape and the disks showed up properly at the >>> prompt, but once booted the tape was missing.
So the disks were operable but not the tape.
I tired both with a terminated cable and an unterminated, same result.

BTW: What does the strap "Term power" mean?

Steven Schweda
Honored Contributor

Re: HP DAT72 and disks on same bus on a PWS

> BTW: What does the strap "Term power" mean?

Power for the terminator resistors (et c.,
depending on how fancy the terminator is).
Someone on the bus must supply it, but one
source is enough. (It's normally safe to
have more than one source. They're designed
to coexist with others.)
Rob Leadbeater
Honored Contributor

Re: HP DAT72 and disks on same bus on a PWS

Hi,

Which Qlogic card are you using specifically ?

> but once booted the tape was missing.

By missing do you mean the /dev/tz* device wasn't present ? (I'm assuming you're using 4.0x). Is it the case that you just need to create the device files with MAKEDEV ?

What does the output of "scu show edt" show you ?

Cheers,

Rob
Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

Well, I was changing my setup without telling, sorry.

This is the situation:

I have now confirmed that the tape and at least two disks can work together on the internal scsi bus provided that "Force Single-Ended mode" is enabled on all disks, using tru64 V4.0F.

I have now

dkc0
dkc100
mkc500

and nothing connected to my LSI Logic KZPCA-AX interface for the moment. My QLogic KZPBR-CY did not work, so I put it aside.

After booting a pre-installed V5.1B-4 disk (installed without the tape or tape connected to a different scsi configuration) I am not able to get the tape into the system. genvmunix/doconfig is NOT doing the trick. Someone suggested it is necessary to REINSTALL V5.1B to detect and get new hardware support. Is this really true?
./MAKEDEV tz21 did not produce any working nrmt0h device. # file /dev/nrmt0h claims scsi id#0 which is not true.

Should some other tool be used in V5.1B to install new hardware?

For now, my prime target is to vdump my 5.1B-4 disk on tape, since I put a lot of work in the configuration of some external hardware support, and I need this physical disk to replace a failing 4.0F system disk on another "production" machine.

I tried to do the vdump operation from the 4.0F disk, but strangely enough, I can mount the /usr/users file system on the V5.1B-4 disk but not / or /usr, Mount claims they do not contain a valid AdvFS file system, while disklabel -l says it does.
So I guess I have to boot on the 5.1B-4 disk to do the vdump, but now I have no tape support in it.
Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

Ok, I think I got it.

# hwmgr -scan scsi

The "mt" command is now working, and also "vdump".

Question:
Which device file is now connected to my tape, if any?
If I do "# file /dev/*mt*" the info I get points to SCSI ID #0, which is wrong, should be 5. The same for /dev/tape and /dev/ntape.

So I am confused.
Any comments?


Steven Schweda
Honored Contributor

Re: HP DAT72 and disks on same bus on a PWS

> My QLogic KZPBR-CY did not work, so I put
> it aside.

If that was actually a KZPBA-CB/CY (lots of
plug-in terminator resistor packs), then I'd
expect it to be a differential SCSI card
("HVD", in modern lingo), so I wouldn't
expect it to work with LVD/SE devices. (I
was once (2002) the only bidder ($8) on Ebay
for a "K2BPR-CX" card. Apparently, no one
else noticed that it was really a KZPBA-CX,
being offered by a seller who read it
wrong.)

> [...] Someone suggested it is necessary to
> REINSTALL V5.1B to detect and get new
> hardware support. Is this really true?

Tell that person to stand on one leg and
scream like a chicken, and then try:

dn_setup -boot

See, for example:

http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1102238

> [...] the info I get points to SCSI ID #0
> [...]

What makes you think that any "0" there is
related to SCSI ID 0? (Is it true for the
disks in "/dev/disk"?)
Rob Leadbeater
Honored Contributor
Solution

Re: HP DAT72 and disks on same bus on a PWS

Can you post the output of "hwmgr view dev"

Cheers,
Rob
Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

# hwmgr view dev
HWID: Device Name Mfg Model Location
------------------------------------------------------------------------------
3: /dev/dmapi/dmapi
4: /dev/scp_scsi
5: /dev/kevm
33: /dev/disk/floppy0c 3.5in floppy fdi0-unit-0
53: /dev/disk/cdrom0c SAMSUNG CD-ROM SC-148P bus-1-targ-0-lun-0
54: /dev/disk/dsk0c MAXTOR ATLAS10K5_300WLS bus-2-targ-0-lun-0
55: /dev/random
56: /dev/urandom
57: /dev/ntape/tape0 HP C7438A bus-2-targ-5-lun-0
92: /dev/disk/dsk1c COMPAQ BD01874554 bus-2-targ-1-lun-0

Ok, I see now that I did not realize the change in device files between 4.0F and 5.1B. "# file /dev/...." does not show the same info as in 4.0F, if any useful at all.
So I will RTFM and study hwmgr instead.

I think all is covered now.

I learnt (by myself actually) not to mix LVD/SE and LVD devices on the same bus;
I learnt not to assume ANY similarities between device management in 4.0F and 5.1B;

Thanks a lot!







Bengt Nilsson_2
Regular Advisor

Re: HP DAT72 and disks on same bus on a PWS

And thanks Steven for informing me about the truth about my KZPBA-CB/CY, it explains a lot.
Closing this thread successfully.
Rob Leadbeater
Honored Contributor

Re: HP DAT72 and disks on same bus on a PWS

Hi,

> I learnt not to assume ANY similarities
> between device management in 4.0F and 5.1B

Device management was one of the major changes between 4.0x and 5.x.

Glad to hear that you figured it out.

Remember to say thanks by assigning points.

Cheers,

Rob