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Mechanical DLT failure

Horacio Moglia
Occasional Visitor

Mechanical DLT failure

We have three units DLT 40i installed in 3 servers: a Netserver LD Pro with WinNT 4.0, and two Netserver LC 2000 with Windows 2000 Advanced Server.
Since the units have been installed, approximately one year ago, we have seen that the units are out of service, without any apparent reason, during the normal operation of backup. The only visible symptom is that all the lights that are to the left, are blinking, and the only solution is to request the substitution of the unit. To the date, we have changed approximately 3 times each unit.
Does somebody exist in the forum to whom something similar has happened? Is there some explanation on behalf of HP concerning this?
Thanks in advance.
3 REPLIES
Mikael Johem
Occasional Contributor

Re: Mechanical DLT failure

When the units worked. What kind of speed did you achive? The DLT40 is able write at 1,5MB/s in native mode and 3,0MB/s assuming a compression ratio of 2:1. If you cant get the drives to stream you will get what is known as "Shoe-Shine-Effect". This means that the drives isnt getting enough data from the filesystem/s you are backing up. When this happens the drive has to rewind and reposition the tape. This type of action wears down the tape head. The only thing to do the is to replace the drive. Several things can cause the "Shoe-Shine-Effect", it can be a slow network (if your backing up remote machines), it can be a filesystem on a slow disk system or it could be that your filesystem is heavilly fragmented. You should run a tool called Performance Assessment Tool to check how much your filesystem is able to deliver to the drives. You can find the Performance Assessment Tool here ftp://ftp.hp.com/pub/information_storage/software/pat12.exe. You should also try running the HP Library and Tape Tools to diagnose your drives. You can find the HP Library and Tape Tools here ftp://ftp.hp.com/pub/softlib/software1/co529/co-1049-2/ltt_27_eng.exe.

Hope this will be of help.


Mikael Johem
Martin Johnson
Honored Contributor

Re: Mechanical DLT failure

The "Shoe-Shine" effect can also be caused by having the disk being backed up and the tape drive on the same SCSI card.

HTH
Marty
Horacio Moglia
Occasional Visitor

Re: Mechanical DLT failure

Thanks for your suggestion
I have executed the PAT utility and the transfer speeds are correct (1,5 MB/s) for the DLT40.
I don't make backup of my network units.
??Maybe a failure in the cartridges causes that the unit is so frequently out of service?