DLT40 reliability issue

[Jonathan Sachs]

I use a SureStore DLT40 drive to back up my home workstation, running Windows XP. Last night an incident occurred which has compromised my confidence in it.

Some history: for nearly 15 years I used DAT drives for backup. I started with an ancient nonstandard drive, and upgraded to DDS1, DDS2, and DDS3 with no serious problems. Last fall, though, my DDS3 drive failed without warning. Later discoveries made me pretty sure that poor grounding and static electricity were the culprits, but at the time the failure seemed spontaneous.

I replaced the drive with another DDS3 drive of a different brand. This drive worked for less than one month before failing; a tape cassette stuck in it, the drive would not eject the cassette because it did not believe anything was there, and I couldn't find a way to get it out. I later found instructions for removing the cassette and discovered that the tape had broken; this may have been just an unfortunate coincidence. The drive still works fine. Meanwhile, though, I decided that DAT technology was no longer working for me and I needed to replace it with something more reliable, namely, DLT.

I then bought a used SureStore DLT40. Up until last night it worked faultlessly. Then I tried to run a backup on a name-brand tape which was new at the start of this month. I had run one full backup on it and appended three differential backups to the end. I was now trying to append a fourth. Instead, the "clean tape" light came on.

OK, dirt happens. I ran a cleaning cycle and put the tape back in. When I started the backup the drive skipped forward to the end of the tape, and then the backup program reported an error. Sometime during this process the "clean tape" light came on again.

I unloaded the tape and ran another cleaning cycle. Then I put the tape back in and tried to run a complete backup, overwriting the tape's previous contents. Once more, the "clean tape" light came on.

Another cleaning cycle. That I put a fresh tape in the drive and ran a new backup with no problems.

It appears that after less than a year of light use, I have just had a practically new tape go south on me with no warning, and for no discernible reason. What can I do to identify and correct the cause of this?

As I said, my confidence in DLT tape is severely shaken. Since this has happened once, why shouldn't it happen again? Unless I can identify the problem and feel confident that corrective action will prevent it from recurring -- permanently -- I'm going to have to write DLT off as a bad idea that seemed good at the time, and find some other backup medium.

[CA713937]

If you have questions about the drive functionality or media performance, you can install the diagnostic tool - HP library & tape tools (www.hp.com/support/tapetools).

You can run the drive assessment test or the read/write test.

You mentioned that this is in a home environment. A cleaning light condition can be caused by a number of factors including normal head staining (from chemicals in the media) to dust or other contaminants (like carpet fibers, paper dust, ink,smoke, etc). The cleaning tape is only lightly abrasive (to minimize wear to the head) and works best for removing normal staining. For other types of contaminants, it may not be as effective (it may just move them around in the drive but not remove them). Sometimes you need to run a cleaning tape multiple times.

[Jonathan Sachs]

Today I ran another differential backup to my new tape with no problems. Then I inserted the old tape and tried to run a partial restore. The restore worked -- BUT -- the cleaning light came on again. (I have not tried running another backup to the old tape to see if it will behave exactly the same as before. I would like to do so but do not have time now.)

Cleaning cycles aside, I seem to have "use cleaning tape" problems whenever I insert this particular tape in the drive, and not at other times. To me it appears even more probable than before that this is about something the drive did to the tape, not about the condition of the heads on the drive itself. Unless you agree with that or can explain the results of my testing in other terms, I would be concerned that the advice you're giving me doesn't really apply to the situation. I hope you can address this in your response in order to dispose of any misunderstanding, on your part or mine, before I try to investigate further.

I have a copy of L&TT installed from when I was trying to diagnose the problem with my original DDS3 drive. It is version 3.4 SR1a -- not the current version -- because the current version proved to be incompatible with my HP DDS3 drive. If I am going to use L&TT now, is this the appropriate version, or should I install the newer one?

[Jonathan Sachs]

This thread appears to have fallen through the cracks. David or someone, could you respond to my previous post, please?

BTW, since I wrote it I have used the drive several more times with the new tape I started, and with another new tape, with no problems. The "old tape -- problems -- new tape -- no problems" pattern is 100% consistent.

[CA713937]

Johnathan,

Sorry, I did not have a reply notification set on this. Just noticed your follow-ups.

> Cleaning cycles aside, I seem to have "use cleaning tape" problems whenever I insert this particular tape in the drive, and not at other times.

The cleaning light indication from the drive is based on its ability to read or write on a tape. It can't really measure that the head is dirty - it merely turns on the light when it has a read/write problem (either a hard error or high soft error counts) for which it feels a cleaning may help.

> To me it appears even more probable than before that this is about something the drive did to the tape, not about the condition of the heads on the drive itself. Unless you agree with that or can explain the results of my testing in other terms, I would be concerned that the advice you're giving me doesn't really apply to the situation.

The problem certainly sounds isolate to the particular tape. I can't state whether the drive "did something" to the tape to cause this, or if the problem really resides with the tape. One possibility is some contamination (e.g. carpet fibers) could have been transferred to the tape.

Earlier you said:

> Then I tried to run a backup on a name-brand tape which was new at the start of this month.... the "clean tape" light came on.

> OK, dirt happens. I ran a cleaning cycle and put the tape back in. When I started the backup the drive skipped forward to the end of the tape, and then the backup program reported an error. Sometime during this process the "clean tape" light came on again.

If you are consistantly getting a hard error on a near new tape and the drive has been cleaned, then I suspect the tape may have a defect. Depending on the media brand, you may be able to have it replaced. HP branded media has a limited lifetime warranty.

You can use HP L&TT to pull a support ticket after a backup (while the tape is still loaded) and look at the write error counters (hard and soft error counts). You can also look to see what errors occured in the drive event log - these are persistent even after the tape is unload (it keeps the last 15 or so reported errors).

If you post a support ticket, I can review the logs for you.

You also said:

> I have a copy of L&TT installed from when I was trying to diagnose the problem with my original DDS3 drive. It is version 3.4 SR1a -- not the current version -- because the current version proved to be incompatible with my HP DDS3 drive. If I am going to use L&TT now, is this the appropriate version, or should I install the newer one?

You can use 3.4 with the DLT40 drive to look at the logs. The only change may be updates to the device analysis rules and the DLT drive assessment test.

I'm not aware of any compatibility issues with the current LTT version (3.5 SR3) and DDS3 drives. If you would email that issue to the ltt_team@hp.com mailbox, we can investigate it. Thanks.

[Jonathan Sachs]

Thanks. I will download the new version of L&TT and ran it as soon as I have a chance -- perhaps not right away, because my life has gotten pretty busy. I will be back when I have something to report.

The compatibility problem with L&TT is described in this forum in the thread â Windows XP backup "Looking for backup devices" very slow,â which I started on June 7, 2004. You can get the information from there. The advice to use an older version came from Dave Dewar, a HP UK representative. Let me know whether it's still necessary for me to report it in view of that.

[Jonathan Sachs]

Today I finally found time to work on this problem again. Unfortunately (or fortunately), it appears to have fixed itself. The tape that I was unable to read or write is now working just fine.

Let me know if it might still be useful to post a support ticket. I can prepare one before the next time I use the drive (Tuesday or Wednesday) if so.

[Jonathan Sachs]

Well, it happened again, or something else did. This morning I inserted my current backup tape in the drive and tried to run a backup to it, and the drive wouldn't recognize the tape's presence.

After trying every imaginable strategy (rebooting, inserting the tape after starting the backup program, starting the backup program after mounting the tape, etc.), I tried a different tape. No problem. I tried the first tape began; nothing.

So, at some point between my most recent backup and today, my current month's backup tape has become a "non-tape." I can't even wipe it and reuse it, since the drive doesn't recognize its presence.

I will run L&TT if you advise me that it is useful, but since the drive doesn't even know the tape is there, I'm not sure it would be.

Any other ideas you have about diagnosing the problem(s) are welcome. At this point I'm really not sure what to do.

Could this problem somehow be caused by turning the tape drive on and off while the computer is on (never with a tape inserted)? That doesn't seem likely to me, but it's the only thing I'm doing that seems at all unusual from the perspective of the drive's developers. Since I need to use the drive about half an hour twice a week, and it makes more noise than the computer itself, leaving it on all the time is really not an acceptable solution, but I'd like at least to know what I'm dealing with.

Could the drive itself be malfunctioning? When I bought it I bought a second, identical one so that I'd have a "backup backup." Perhaps it's time to put the second drive in service. If switching drives doesn't solve the problem, though, I may not find out for months, and then I may find out by discovering that I can't do a restore.

I've been using the DLT drive for about 10 months now, which means that I've gone through 10 monthly backup tapes, and in that time I've had two failures. A failure rate of somewhat over 20% per year really does not sound very good for backup media. If I can't identify and correct these problems I will have to write off the DLT drive as a nice idea that didn't work out, and find something else.

[CA713937]

Johnathan,

If you can generate a support ticket for the drive from LTT (support -> save ticket to file), and then post it here I can look at the drive event logs to see what it may have reported for the tape that will not load (as well as reviewing any previous failures for R/W issues, servo issues, etc).

[Jonathan Sachs]

The ticket is attached. Before creating the ticket I (1) inserted a tape which the drive recognizes, then ejected it and (2) inserted the tape it no longer recognizes.

I noticed this time that when I insert the problem tape the "use cleaning tape" light goes on again. This came as no surprise, since the light seems to mean nothing more specific than "something went wrong."

I made this ticket with L&TT version 3.4 SR1a. I know that a much more recent version is available, but I wanted to avoid updating because I had nightmarish problems with L&TT when I was using a DAT drive, and I was only able to solve them by "downgrading." Now that I have successfully created a ticket, I can update the program and try to create another one if that would be useful.