A4853A DLT Library with 2 DLT 7000 -- Library NO_HW

[nibble]

Ive got an A4853A DLT Library with 2 DLT 7000 on it. its connected to a K580 server, running in production with data protector.
This set up has been running fine for a long time, though there's an issue with the 2nd drive of having scsi reset. this is due
to the fact that 2 DLT 7000 (cascaded) plus the Library/Robotic as part of the chain, connected directly to a single bus. SCSI resets
has been accepted already as part of the configuration. SCSI address on the library config is 0 (library), 1(1st drive) & 2(2nd drive).
no changes from the original config.

Just recently, data protector says it cant find the picker with error message as:

" /dev/rac/picker: cannot open exchange controller device". power cycled the library. look at the host machine and run ioscan

ioscan says its NO_HW:

target 20 10/8.0 tgt NO_HW DEVICE
autoch 0 10/8.0.0 schgr NO_HW DEVICE HP A4853A

but the 2 DLTs are claimed and functional.

Tried the following:
- removed the device drivers and reinstall them, using "rmsf -H hw path, then insf -e -H hwpath"
- connect directly the bus to the library, w/o the drives,
- combine 1 drive + the library in the chain
- reseat/replace the board of the library
- reseat/replace the picker of the libary
All of these with combination of power cycle of the library, remove, reinstall device drivers, still ioscan says NO_HW but the drives are being seen if they are combined.

- on the library itself, no errors in the status display
- NO light/ No alarm on the Service Required LED
- Library Active LED is blinking
- run diagnostics & demo mode all is well
- Status display is normal but after a while, the last 2 lines becomes
DLT7000 Unit Chk
DLT7000 Unit Chk

Reboot was the last resort, but its a critical machine so until now, no clearance for it. Any help will be highly appreciated.
I was wondering whats the "unit chk" means though.

[OldSchool]

1) I doubt that a reboot will fix this as ioscan can't find it

2) SCSI resets are not a "normal" condition, regardless of your configuration. If you're running EMS, that may have caused it, but it's doubtful.

3) My first inclination is to check that the cables / terminators are correct.

4) I've not used this particular library, but I believe that the electronics are available in SE-SCSI as well as WideDiff. Are you sure the installed controller matches the card on the bus? I've had a situation where (on a new library) the robotics were of one type and the drives of another....which doesn't work but passes self-tests perfectly

5) It could be that the picker/controller will have to be replaced. Even if that were dead, it I believe it would still see the drives.

[Torsten.]

I try to remember this old box, but I'm not sure about this.

Anyway, most libraries in that style can be switched to single-ended or differential for the controller device.

If you changed that device, make sure the setting is correct.

BTW, it was not allowed to have 2 DLT7000 drives on only 1 bus for this box.

Maybe the defective/wrong set controller device is disturbing the bus, for this reason you get a check condition from the devices.

[nibble]

hi old school,
i jes wonder if its cable or terminator, its been working for a long time and jes happened now now.

[OldSchool]

I kind of doubt it, as it can see the drives...I assume from your description the cabling goes from bus to picker, then daisy chain the drives.... If that's the case, and the cable were bad, I would assume you couldn't see the drives either.

Couldn't find anything related to the "Unit Chk" message either...

My best guess (and thats all it is) is that the picker and its electronics need replaced.

[nibble]

Thanks to all.