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HP C1537A compression test failing - please help

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Jacob Durham
Occasional Advisor

HP C1537A compression test failing - please help

Hello All
I am using a HP C1537A (1554) tape drive and Backup exec 9.0 Win2k server addition and my backups stopped several days ago hanging on loading media. The tape has about 4 gig of data written to a 12/24 dds-3 tape and has a compression ratio of about .4:1. This happened for a week an then I downloaded L&TT, did a firmware upgrade and ran the tests. They all passed except the compression test which failed. Where do I go next?
Thanks in advance.
15 REPLIES
David Ruska
Honored Contributor

Re: HP C1537A compression test failing - please help

Send the eventlog files (EventLog*.ltt in the logs folder) to ltt_team@hp.com, and I'll take a look at why the compression test failed.
The journey IS the reward.
Jacob Durham
Occasional Advisor

Re: HP C1537A compression test failing - please help

Thanks David. I've attached the file.
David Ruska
Honored Contributor

Re: HP C1537A compression test failing - please help

Jacob,

This is an interesting one. It looks like the compression test fails when you ask to enable compression. If you don't say to enable it, then it passes (but with 1:1 compression).

When the test fails, it fails for an "ILLEGAL REQUEST, Invalid field in parameter list". It is behaving like the data compression switches (SW1 & SW2) are set to disable host control, no compression (SW1&SW2 off). However the script read the config switch settings as "0xFB" which is all but SW3 set to ON (which allows host control).

Could you generate a support ticket and post the .ltt file?

Can you manually check your switch settings?
The journey IS the reward.
Jacob Durham
Occasional Advisor

Re: HP C1537A compression test failing - please help

At this time, I have removed the tape drive and reinstalled it and I'm running a backup job now. The switch settings are correct all on except 3. I had already created a sticket and I'll attach it now.
David Ruska
Honored Contributor

Re: HP C1537A compression test failing - please help

Jacob, sorry you had to remove the drive to check the swtiches (didn't realize it was an internal drive).

Everything checks out fine in the support ticket. It says switch 3 is the only one that is off. The host should be able to control compression (and the default should be On).

It says the current configuration is "data compression disabled". That confirms that host control of compression is enabled (otherwise it reports as "not present")

Before running LTT, did you disable your backup services (and Windows Removable Storage Manager)?

Did the compression test failure start after the firwmare update, or don't you know?

I don't have any other ideas, so I'll need to run this by some folks in engineering.

If you want to try going back to the older code (L105), send an email to ltt_team@hp.com, and I'll send you an LTT password.
The journey IS the reward.
David Ruska
Honored Contributor

Re: HP C1537A compression test failing - please help

Jacob,

Duh, I feel dumb. I worked on an identical issue back in December. We found that windows backup was setting the compression algorithm to zero, so when LTT tries to enable compression, it fails for an illegal request (you can't have compression enabled without an algorithm set).

Here's the previous thread:
http://forums1.itrc.hp.com/service/forums/bizsupport/questionanswer.do?threadId=242271

I think you'll find that if you power-cycle the drive (that also means the server for you), the test will pass until you run a backup.

We have an improved version of the LTT compression test, which I'll attach here. Put this into the LTT scripts folder.

Try this version, and see if that resolves the compession test failures.
The journey IS the reward.
Jacob Durham
Occasional Advisor

Re: HP C1537A compression test failing - please help

Thank you David but I'm not all that concerned about the test now unless it will lead to me getting a backup of my data. It's been a week now. The backup I ran last night after reinstalling the tape drive failed again on loading media after it ran for 2.5 hours. The tape properties in BackupExec are reporting the tape as full (11.2 GB) with only 4.2 GB of data being written to it, a compression ratio of .366:1.
The XML file generated by BE said
"----- TapeAlert Events -----



Warning - The tape drive is having problems writing data. No data has been lost, but there has been a reduction in the capacity of the tape.
Robotic Library:
Drive: HP 1
Slot:



Critical - The tape drive needs cleaning:
1. If the operation has stopped, eject the tape and clean the drive.
2. If the operation has not stopped, wait for it to finish and then clean the drive.
Check the tape drive users manual for device specific cleaning instructions.
Robotic Library:
Drive: HP 1
Slot:


The tape has been cleaned many times recently. Is it a possibility that the drive is damaged? Are there any other scripts that I could run to further test this drive?
David Ruska
Honored Contributor
Solution

Re: HP C1537A compression test failing - please help

The tape alerts are indicitive of error rate problems.

If the drive logs are correct, it says you are running with a duty cycle of 47%. The drives are speced for only 5 Hours/day. The logs also indicate a lot of repositioning, which might indicate the drive was not being kept streaming. It also indicates only 3 cleaning cartridge loads. If that is correct, you have be seriously undercleaning (you should clean once a week, or once per every 5 full tapes).

One thing the device analysis doesn't recommend is the write recalibration. This is a procedure done when the heads appear to be worn.

I would suggest you clean the drive 5 times with a new cleaning tape, and then run the read/write test on a new tape. It will display the average transfer rate. The last time you ran it, it was only getting .3 MB/sec.
The journey IS the reward.
Munir_1
Trusted Contributor

Re: HP C1537A compression test failing - please help

Looks like you also sharing 2 hard drive with the tape drive, that will cause the tape drive to run slow and for the drive to keep streaming.
Isolate the tape drive on its own PCI SCSI Card. Even that it might worked ok in the Past, its not recommended to share tape drive with any other device, specially the hard drive
David Ruska
Honored Contributor

Re: HP C1537A compression test failing - please help

Yes, if those disks are the ones being backed up, that will affect your performance and cause unnecessary repositioning. You should have it on a separate HBA.

Good catch Munir.
The journey IS the reward.
Jacob Durham
Occasional Advisor

Re: HP C1537A compression test failing - please help

Can you please enlighten me as to the effects that the block size in the drive configuration properties has on all of this.
I really appreciate all of the help.
David Ruska
Honored Contributor

Re: HP C1537A compression test failing - please help

Sure, look at this web page:
http://h20015.www2.hp.com/hub_search/document.jhtml?lc=en&docName=lpg50167
The journey IS the reward.
Jacob Durham
Occasional Advisor

Re: HP C1537A compression test failing - please help

Thanks, thats the article I read that got me to ask the question. Mine has been set to the default which is 8K. I guess what I wanted to know was should I increase it to 32K to increase performance.
David Ruska
Honored Contributor

Re: HP C1537A compression test failing - please help

Yes, but it may be too late (if you wore the drive out by repositioning it for a long time).
The journey IS the reward.
Jacob Durham
Occasional Advisor

Re: HP C1537A compression test failing - please help

Thanks again for all of your help. The cleaning tape is not working now after a couple of tries. I ran the read/write test again and received results of .5 and .7 MB/sec transfers. I'm going to get a new cleaning tape and look into new SCSI cards.