%META:TOPICINFO{author="ChrisBartram" date="1219015811" format="1.1" version="1.2"}%
%META:TOPICPARENT{name="Hp3000DdsUnits"}%
To prevent problems with your tape drive, keep the following list in mind: 

* Are your tapes DDS certified? This is indicated by a DDS (Digital Data Storage) symbol on the tape. 

* Do you replace your tapes on a regular basis? HP recommends tape replacement after approximately 300 uses. 

* Do you clean your drives at regular intervals? Drives should be cleaned after 25 hours of use (Calculate this at approximately 2 hours for each tape use) or whenever the Cassette indictor light flashes the Caution signal (indicated by an alternating green light for 4.5 seconds and and no light for 0.5 seconds.) 

* Do you replace the cleaning cassette at regular intervals? Each time a cleaning cassette is used, the date of use should be marked on the label. After 25 cleanings, the cleaning cassette must be replaced. If you fail to record each use of the cleaning cassette, after 25 uses the cleaning cassette may appear to be working normally, but it will be doing nothing. A working cleaning cassette will take about 54 seconds to clean the drive, a used up cleaning tape will take about 11 seconds. 

* If you are having problems with a tape drive reporting that tapes are bad, and you suspect that the tapes are ok, HP recommends cleaning the drive three times in a row. If the problem still persists, place a call to have the drive replaced. 

 --[[MarkRanft]]

FWIW, the "needs cleaning" indication is completely different for the HP6400 model 4000[DC] drives, as are most of the other indicators. 

 --[[SteveDirickson]]

DAT's - gotta love 'em, gotta hate 'em...

One bad problem with DATs , especially DDS2s, is that the heads tend to drift out of alignment long before they give a failure.  This means that your heads have gotten out of factory alignment - not so bad that the tape drive errors, but bad enough that another tape drive will not read its data.  This was really bad with the DDS2s - a client would finally have a drive go fulltime bad (finally drift out of tolerance) and then not be able to read their tapes when a new, factory aligned drive is installed, and this could be months worth of backup information.

I have found that sometimes going to a higher density drive will allow a little more tolerance, ie: using a DDS2 tape in a DDS3 drive can sometimes recover the data.  It has been procedure around CTS for quite some time to replace all DDSs and DDS2s DATS with DDS3s for just this reason.  The higher density
DDS3 does not seem to tolerate drift as much as the earlier versions, thus
DDS3 tapes tend to not have this problem as bad as the DDS, DLZ and DDS2.

A tape drive does not mark a tape as bad when it is encountered - how could this work with the write tape disabled - it does however flag the drive for cleaning when this is encountered too often.  Watch for this recurring error, it is a clue.  If the cleaning does not fix the problem, or it re-occurs frequently, then this is a sign that the head is drifting and you may be losing all integrity in your backups regarding information recovery on another tape drive.  I have seen this happen on DR tests - known good tapes from an online drive cannot be read on the DR system for just this reason - incompatibility between the drives.

Quick fix - two tape drives in house - write on one, verify on the other, or alternate the read and write drives.  Much like verifying backups, this is usually the leason you wish you had learned about ten minutes ago...

--[[BrettForsyth]]

-- Main.ChrisBartram - 17 May 2006