LTT: Support Ticket doesn't include all LTO Drive Assessment Data

[RalfG]

Hi,

I've a FC LTO-4 drive which seems to have some problems when writing to tape. So I'm running the HP LTT LTO Drive Assessment test on Linux.


./hp_ltt -f test p="90.0.0[9-/dev/sg12]" testname="LTO Drive Assessment test" testopt="Allow Overwrite:True" testopt="Amount of Media to Test:Entire Tape" testopt="Number of Iterations:10"

The test only takes a couple of minutes, I'm sure not the whole tape was used for this test and at the end of the test I get the following in RsltLog.ltt:


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.


What I also see in the Log is this:

Please note: the operations performed by this overwrite test will NOT be reflected in the Support Ticket usage/health information.


After that I created a support ticket.

./hp_ltt -f ticket p="90.0.0[9-/dev/sg12]"

But this support ticket does not show any problems with this drive at all:

Device Analysis has checked the fault logs. No problems were found and the drive is good.


Now I'm confused what I'm doing wrong and what information is correct.

Attached are the Support Ticket and the Logs.

[RalfG]

Event.log

[RalfG]

I'm not able to attacht the RsltLog.ltt, I tried it 6 times now. Either I only get a blank page, or a message that the posting was ok, but the post with the attachment doesn't show up...

[Dennis Handly]

>I'm not able to attach the RsltLog.ltt,

You can't attach over 1 MB. You could try to gzip/zip it and see if it is small enough.

[RalfG]

it was just 23KB...

[Víctor Cespón]

Hi, opening your first attachment with L&TT I see the drive in perfectly good shape:

Product ID : HP Ultrium 4-SCSI
Firmware : H43H (Ver 012.169, Date 2008/03/12-19:05)
Device Analysis : Passed
Write (last 2 tapes) : Great margin (801 GB)
Current tape load count 502 : Great margin (1.5 MB)
Read (last 1 tapes) : Great margin (395 GB)
Head life : Great margin, 99% life remaining
Reposition life : Great margin, 99% life remaining
Load/unload life : Great margin, 99% life remaining
Cleaning tape requested : No
Current temperature : 32.1 C - Great margin
Power on time : 243 days, 0 hours, 32 minutes
Tape Pulled : 164.4 full volume equivalents
Load/unload cycles : 502 (0% of expected life)
Duty cycle : 12%

(no host-reported errors found in the fault logs)
No problems have been identified with the drive mechanism.
No problems have been identified with the drive PCA.
No write / read problems were identified with the drive.
No cartridge related problems were identified with the drive.

Maybe you have problems on the FC link to it? Can you check the switch logs?

Also, are you using HP tapes? The drive history seems to have mostly Maxell, Imation and Sony.

[Dennis Handly]

>it was just 23KB

You may want to zip it anyway, if it doesn't like your suffix? (Make sure you capitalize .ZIP because the forum and IE don't like .zip.)

[RalfG]

RsltLog.ltt.gz

[RalfG]

@vcespon

That's what confuses me. The drive and media assessment test both say the drive is bad. But this information is not included in the ticket.


part of the event log (grep for the string margin)

EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText:Drive margin (from last Assessment Test run)\: 0%:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Drive measurements\: Great margin:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Write/read life\: Great margin:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Load/unload life\: Great margin:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText:datasets written 7658 write margin 4%:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Write margin (wrap 0)\: Fair margin (11.3 GB written):1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText:datasets written 8219 write margin 43%:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Write margin (wrap 1)\: Good margin (12.2 GB written):1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText:datasets written 6267 write margin -93%:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Write margin (wrap 2)\: Warning (9.3 GB written):1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText:The drive could not write data to the data cartridge with sufficient margin.:1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Overall Margin\: Warning (32.8 GB written):1252:0
EventLog.ltt:10:4:4:40:3:3:42:1:1:PlainText: Wrap 2 Margin\: Warning:1252:0


I used a HP tape for these tests. The problem was noticed during a backup with a Maxell tape. Both tapes work perfectly fine in other drives.


This FC LTO-4 drive is already the 4th drive we got as replacement.

[RalfG]

Hm, is nobody here who can tell me something about the ResltLog or EventLog?

[Curtis Ballard]

I have asked to look into whether we can make things any more clear in this area.

What is happening here is that the assessment test using a built in test which suspends the normal logging and reports all of it's data in the results. If the test encounters a problem that it considers fatal it will stop right away instead of running the full cycle since that won't change the pass/fail results.

Since the normal logging was suspended during the built in test that assessment runs the results don't show up in the device analysis section of the support ticket. There is a test history section that will show the same failure that you saw at the end of the test.

[RalfG]

Ok, thanks. So from looking at the output/data of the assessment test, you would consider this drive as bad?

I'm a bit worried, because this is now the 4th FC LTO4 drive that fails. The 2 SCSI drives in the Lib seem to be more reliable, even though they are much more in use.

[Curtis Ballard · Accepted solution]

I always like to get at least two failures with different tapes before I declare a drive. Best case run a media assessment with a drive that has been working well and make certain that passes then run the same tape in the drive assessment test on the suspect drive. If that says the drive is bad it almost always is.

I'm concerned that you have had several drive failures. That isn't normal and there really shouldn't be any difference between FC and pSCSI drives in the head/media interface. Is there any chance that you have media pools and the media used with the FC drives is different from the media used with the pSCSI drives. I have run across a few pieces of abrasive media that can wipe out heads. It is also possible for media to get contaminated and transfer the contamination to the heads when loaded into a drive. Sometimes that can be corrected by cleaning the drive multiple times.

[RalfG]

I tested the drive with the used Maxell tape and a brand new HP tape. But I've only the Assessment Test data of the latest test.

Both tapes were used in the SCSI drives after that and didn't show any issues.

I'll repeat the test with 2 new tapes after cleaning the drive's head several times (again). I'll attach the logs then, this may take some days.

[RalfG]

I've now tested all 3 drives with a new HP LTO-4 tape. The two SCSI drives seem to be ok, the FC drive has failed the Drive Assessment Test.

Attached is the RsltLog.ltt with the results of all 3 tests.

Is it possible to see, why the FC drive is bad?

[Curtis Ballard]

The FC drive was marked as bad because the drive had to perform too many rewrites. There are almost always some rewrites but extra space is built in to handle that. When all the allocated space for rewrites is used up L&TT will flag the drive as too worn even if the drive is still able to successfully read/write.

In this mode it is fine to continue to use the drive and the write threshold is so high that there should never be any issue with reads but the performance and capacity may not quite meet specs.

I might mention that the first drive you tested is within specifications but also shows that it is using a fair amount of rewrite space.

[RalfG]

Thanks for the info. The FC drive is writing very slowly to tape (40-50 MB/s)

I'll contact our dealer and let him replace the drive, maybe the SCSI drive too.

Still wondering why we have so many bad LTO-4 drives. We use a tool named Veritape (http://www.mptapes.com/) to check the tape regularly. Many of our LTO-4 tapes have a score of 75-90 after 1,5 years of usage, some are only writen 2-3 times. Our LTO-3 tapes (IBM LTO-3 drive), all have a score of >90 after more than 3 years. Never had a problem with the LTO-3 drive or a single tape. That makes me worry...

[Curtis Ballard]

The pSCSI drive isn't elligible for replacement based on the wear numbers - it's still in spec. I just thought I would mention that it does show some so it isn't that the one drive is FC.