  parity errors on DDS (DAT) tapes? 
 The Question is:
 
Hi,
We have been having problems with our disk drive while taking regular
backups. We use sony dg90m tapes(2 GB) for these backups. The machine is
digital alpha server 2100. The tapes do not backup regularly as there is a
parity error on the backup tapes. Is
this a problem with the tapes or with the disk drive itself. What bpi should
the tapes have and what are the tapes recommended. The parity error occurs
even after we use new tapes. The tape is a 4mm tape.
 
 The Answer is:
 
  The Wizard would recommend contacting your hardware support organization
  for assistance with this problem.
 
  When asking these sorts of questions, please identify the specific type
  of hardware involved -- in the case of DDS (DAT) backups, the specific
  model of the DDS tape drive will be of central interest.
 
  DDS tape drives are restricted on the length of the DDS cassette that can
  be used, with older DDS tape drives unable to reliably use DDS cassettes
  longer than 60M.
 
  The Wizard would also recommend using the cleaning cassette at the interval
  recommended by the DDS tape drive manufacturer.  (This can be as often as
  every 25 hours of use or every two weeks, whichever comes first.)  Various
  manufacturers recommend four (4) consectutive passes of head-cleaning
  whenever read- or write-related errors are suspected.  Also realize that
  each cassette is good for a certain number of head passes -- 2,000 passes
  is one common value -- and this value is significantly less than the number
  of BACKUPs the cassette was used for.
 
  Various DDS cleaning cassettes are good for approximately 25 passes.
 
  As for the specific DDS drive compatibilities:
 
    TLZ04 is limited to 60M DDS-1 cassettes.
    TLZ06 supports 60M and 90M DDS-1 cassettes.
    TLZ07 and TLZ09 support 60M and 90M DDS-1, and 120M DDS-2 cassettes.
 
 
