Performance with FC Ultrium 4-SCSI LTO4 drive

[Curtis Ballard]

Regarding the support ticket - sorry I didn't think about you may be using an OS that didn't have a native L&TT install. You can pull the support ticket using the library web interface and selecting the drive that you want. That method doesn't require installing L&TT but you have to have L&TT to read the resulting ticket. If you just post the ticket here you don't need L&TT.

The XML file is really difficult to read, an "ltd" is the default and much preferred. If you have an ltd for posting that would be appreciated.

From the XML file I was able to pick out a couple of things. The HP LTO drives have a built in head cleaner and there are several calls to clean the head with that so it appears that the drive thinks that it needs cleaned but if you cleaned it then the problem may be more than cleaning needed.

Back 62 hours ago the drive reported a defective tape with a poorly written servo track - that may match to the batch of bad tapes you mentioned. If a tape with a poor servo track is being used some tape drives will have more trouble than others since the drive will be working at the extreme edge of it's capabilities to track the tape. It's possible that this particular drive just can't follow those servo tracks but I can't tell that from the XML file, I would need the ltd. Not being able to follow bad servo tracks wouldn't indicate a drive hardware problem since the drive would be able to follow a correctly written servo track just fine and would probably follow a servo track written badly on the other side of the specification when drives that follow this servo couldn't.

[RalfG]

I can't find a way to generate a ltd type support ticket. The hp_ltt cli tool for linux only creates lzt or xml files. As far as I can see the ltd is part of the lzt file. So I'll attach the lzt file and additionally the html report I created from the lzt with the Windows LTT tool.

Regarding the bad tapes: all were exchanged weeks ago, so there shouldn't be any left. The 3 tapes I use now for testing are from a different production date and work fine in the SCSI drives (the bad tapes had problems in all drives).


In the generated report I messages regarding cleaning but the lib tells me cleaning is not needed (today I tried again 2 write cycles starting at 000044:54:55.267456 and ending at 000045:06:25.218496):


000045:04:13.707008 Clean |MechInterface commanded to brush the head.

Am I right that this is the internal cleaning that happens automatically?

[RalfG]

and the compressed html report...

[RalfG]

I started an Assessment test. The output doesn't look very promising.... (I've also attached the RsltLog.ltt file)


|__ Test 'LTO Drive Assessment test' started on device 'HP Ultrium 4-SCSI' at address 'a0.0.0[10-/dev/sg10]'
|__ executing LTO Drive Assessment Test...
|__ LTO Drive Assessment Test, version V19.08.2008
|__ Test run: Wed Aug 5 11:00:50 2009
|__ Drive serial number: HU18081FDV
|__ checking tape load ...
|__ Data Cartridge Information:
|__ Vendor: MAXELL
|__ Format: LTO-4
|__ Serial Number: 1280077913
|__ Barcode:
|__ ANALYSIS OF HISTORICAL INFORMATION (from drive logs):
|__ analyzing device data...
|__ updating device writeback data...
|__
|__ version: V19.05.2009
|__ There were 19 rules checked.
|__ Device Analysis has checked the historical information and no problems were found.
|__ RESULTS OF TESTS ON THIS DRIVE
|__ [Please note: the operations performed by this overwrite test will NOT be
|__ reflected in the Support Ticket usage/health information.]
|__ Amount of data requiredâ test option : Default
|__ erasing ...
|__ soft unload ...
|__ loading ...
|__ Iteration number: 1 of 4
|__ writing wrap 4 ( iteration 1 / 4 )...
|__ Write margin (wrap 4): Great margin (13.3 GB written)
|__ writing bottom wrap ( iteration 1 / 4 )...
|__ Warning: Drive is showing a large variation between channels.
|__ Write margin (bottom wrap): Warning (6.8 GB written)
|__ Overall Margin: Warning (20 GB written)
|__ Wrap 29 Margin: Warning
|__ soft unload ...
|__ loading ...
|__ erasing ...
|__ The LTO Drive Assessment Test has checked the history and/or operation of the selected drive, and
|__ problems have been reported.
|__ The drive is no longer recommended for use.
|__ Please contact hp support for further assistance.
|__ Test time: 6:05
|__ Test failed. See the analysis results in the test operations log.
|__ Test failed
|__ Failed

[Curtis Ballard · Accepted solution]

It looks like one channel in the head is almost completely out requiring lots of rewrites. There are a couple of other channels where the signal quality is lower than recommended so I would agree with the assessment test - drive needs replaced.

PS - yes the ltd files are embedded in the lzt files. When saving a support ticket from a library web interface you get an ltd and when using the L&TT tool it bundles and compresses all of the ltd files from one library log set into an lzt file.

[RalfG]

The drive was replaced today. The new drive doesn't show the problem and passes the Assessment Test.

Still a bit uncertain why we have to replace these drives so often (without beeing used much yet).

Next time I'll beginn with the assessment test...

[RalfG]

drive war replaced