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SDLT320 Positioning errors

 
oxygene65_1
Advisor

SDLT320 Positioning errors

Has anyone experienced a problem with SDTL320 tapes/drives when it comes to positioning at the end of the tape ?

For instance. When performing a backup you want to write to the end of the tape.

In my case I have a drive that tries to do this and over the course of a 10 hours will mount verify indefinately until you abort the batch job. In one recent attempt it mount verified 117 times before it was spotted and the job aborted.

The drive has been cleaned, and this happens with diffrent tapes.

Is it an issue with the drive or the firmware on that drive ? What steps can I perform to look into this problem in further detail ?

My drive is housed in an MSL5026 tape jukebox, and I use ABS (Archive Backup System) to perform my backups.
11 REPLIES 11
P Muralidhar Kini
Honored Contributor

Re: SDLT320 Positioning errors

Hi,

>> The drive has been cleaned, and this happens with diffrent tapes.
This means the problem may not be with a particualr tape.

Is the problem seen with only particular drive or with all the drives?

>> My drive is housed in an MSL5026 tape jukebox, and I use ABS
>>(Archive Backup System) to perform my backups.
How does the MDMS load/unload command behave on the drive.
i.e. just loading/unloading of the volume to/from the drive.
Is that only backup's are failing or even the load/unload of volumes
in the drive are also failing.

Regards,
Murali
Let There Be Rock - AC/DC
oxygene65_1
Advisor

Re: SDLT320 Positioning errors

Hi Murali

Loads / Unloads and all jukebox commands are working fine.

Cheers

James

Re: SDLT320 Positioning errors

Hi,

1) Is there any particular error message you are seeing in the ABS log files (SAVE log file)?

You may also want to post the ABS logfile as attachment.

2) Is the error count on the MK or MG device increasing when you face the problem?

$ show device /FULL
--> Error Count: xx

3) You can also check ERRORLOG.SYS for any errors logged against that device.

Regards,
Deepa
Shriniketan Bhagwat
Trusted Contributor

Re: SDLT320 Positioning errors

Hi,

Did you try with BACKUP command from the command prompt, without ABS?

During the save operation on tape, BACKUP possitions the tape to the logical end of the tape i.e. double end of the tape mark.
You can also position the tape from the command prompt using the $ set magtape command.

Regards,
Ketan
Shriniketan Bhagwat
Trusted Contributor

Re: SDLT320 Positioning errors

Hi,

How old the tape is? Are you able to mount the tape drive using the $ mount command from the command prompt?

Regards,
Ketan
Shriniketan Bhagwat
Trusted Contributor

Re: SDLT320 Positioning errors

Hi,

Are the available latest patches installed in your machine?

Regards,
Ketan
Bob Blunt
Respected Contributor

Re: SDLT320 Positioning errors

Oxygene65, let's start with some of the usual basics:

System type?
O/S Version?
Installed patches (specifically what UPDATE, Fibre-SCSI, DRIVER, BACKUP, SYS patch versions)
HOW is the tape connected to your system?
(SCSI controller type, SAN, NSR, etc)
Error status of the tape drive in question.
AND some idea of the BACKUP command being used.

Yes, you would prefer using all the tape in the cartridge. However, how that works depends on the BACKUP command switches. The tape drive senses PHYSICAL EOT (reflective metalic strip, optically, whatever) and this tells BACKUP (or your particular tool used to write to tape) it's time to finish writing the block it's writing and then to mark the tape with the double LOGICAL EOT. Then the software should signal the drive to rewind to verify or rewind and dismount. It depends on your BACKUP string (or equivalent) what it does there.

If you're not *getting* to the physical EOT due to a series of errors (usually notable at the DCL level and in errorlog) then you need to find out what the errors are. If you're in a SAN with the tape behind a NSR or something similar (or even more complicated, an encryption device) then you might have to trust that hardware to give you diagnostic information instead of OpenVMS's error tools.

By the way, under certain circumstances that you can control, it is possible to physically dismount a tape from it's supply reel while writing the last block(s) out "after" physical EOT. It isn't as common with high-density cartridge drives. But IF you're using one of the largest values for the /BLOCK switch I've seen it happen. Just another reason that knowing the specifics of the BACKUP command in use.
oxygene65_1
Advisor

Re: SDLT320 Positioning errors

The problem has been resolved. Thanks to all for your feedback and assistance.

After all of that the culprit was the SCSI terminator hanging off the back of the drive.

I replaced and rebooted the system and all the tape positioning problems and mount verification problems disappeared.

Thanks for all your help.
P Muralidhar Kini
Honored Contributor

Re: SDLT320 Positioning errors

Hi,

Refer the following link which says how you can thank this forum
http://forums11.itrc.hp.com/service/forums/helptips.do?#28

Regards,
Murali
Let There Be Rock - AC/DC