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

 
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Curtis Ballard
Honored Contributor

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

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
Frequent Advisor

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

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
Honored Contributor
Solution

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

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
Frequent Advisor

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

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
Frequent Advisor

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

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
Honored Contributor

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

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
Frequent Advisor

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

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
Honored Contributor

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

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.