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Replace faulty DLT and now performance is bad

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Vermeulen Peter
Frequent Advisor

Replace faulty DLT and now performance is bad

2 days ago we had an HP engineer on site and he replace our DLT drive. The next morning we noticed that backup was still running when coming in the office. It took about 1/3 extra time to finish.
We had HP come on site again and they downgraded the firmware of the DLT back to the same version as the original one.
Today the problem is still the same. Backup performance is still bad.

Can somebody give an indication why this is?
8 REPLIES
Vermeulen Peter
Frequent Advisor

Re: Replace faulty DLT and now performance is bad

# ioscan -funC tape
Class I H/W Path Driver S/W State H/W Type Description
================================================================
tape 1 10/4/4.3.0 tape2 CLAIMED DEVICE Quantum DLT4000
/dev/diag/rmt/c6t3d0 /dev/rmt/1mn /dev/rmt/c6t3d0BESTb
/dev/rmt/1m /dev/rmt/1mnb /dev/rmt/c6t3d0BESTn
/dev/rmt/1mb /dev/rmt/c6t3d0BEST /dev/rmt/c6t3d0BESTnb


If you look at the above output of ioscan, our Quantum DLT seems to be bound to a tape2 (for DDS-drives)driver. I believe this should be driver stape (for DLT's).

How can we modify this? Just by removing the device files and recreating them with insf -e ?
Is a reboot required ?
Eugeny Brychkov
Honored Contributor

Re: Replace faulty DLT and now performance is bad

Hello,
do you have any old ioscan outputs to check if old drive was with tape2 driver? BTW, to which controller do you have drive attached? Attach complete 'ioscan -fn' output here
Eugeny
Vermeulen Peter
Frequent Advisor

Re: Replace faulty DLT and now performance is bad

complete ioscan attached.

No old ioscan available at the moment.

Something strange as well:

# lsdev -d tape2
Character Block Driver Class
# lsdev -d stape
Character Block Driver Class
205 -1 stape tape
#


It seems that tape2 is not loaded properly.

The HP engineer says that although it is a DLT drive, it can happen that the machine sees it as tape2 depending on the type of the hardware (card or something).
Eugeny Brychkov
Honored Contributor
Solution

Re: Replace faulty DLT and now performance is bad

Correct, that's why I asked you to which controller drive is connected to. From ioscan I see that you tried to change drive's SCSI Id to see is anything will change. Nothing. The same. Drivers are correct: scsi3 for hp-pb SCSI card, and tape2 for hp-pb connected tape drive.
As soon as setup is correct and drive is new and functional, nothing changed in software (for example, block size), but speed decreased you can try HP LTT checking drive and running tests http://www.hp.com/cposupport/information_storage/support_doc/lpg50128.html , but before doing it please check all SCSI connections are secure, there're no bent pins, terminators are in place. Which drive (product number) do you have? Is it possible that this drive has option to turn on termination internally to the drive (to the box, so the bus got overterminated)?
Eugeny
Vermeulen Peter
Frequent Advisor

Re: Replace faulty DLT and now performance is bad

In the hp_ltt the tape device doesn't show.

XSTM gives me this nfo
The following information was archived during the last hardware scan:

Product : SCSI Tape
Qualifier : QuantumDLT4000
Hardware Path : 10/4/4.3.0
Device Type : Tape
Device Qualifier : DLT
Vermeulen Peter
Frequent Advisor

Re: Replace faulty DLT and now performance is bad

I read this in the manual, so that's why the tape doesn't show.
L&TT does not support the NIO bus type. If your system has an HSC or PCI
bus, connect your device to that bus. If your system does not have an HSC or
PCI bus, unfortunately, L&TT will not work for you.
Eugeny Brychkov
Honored Contributor

Re: Replace faulty DLT and now performance is bad

I'm sorry :o(
Did you check cables? What's drive product number (look at the sticker on the drive's casing)? First letter should be A or C, then 4 digits and then one more letter, like 'C7145A'
Eugeny
Vermeulen Peter
Frequent Advisor

Re: Replace faulty DLT and now performance is bad

We did a reboot late friday night when there was no production.
The backup that run after that was back to normal.
I think there must have been something with the SCSI bus when we disconnected and reconnected the drive.
thanks all for the help.