Overview of the DAT Drive
1-3
Compaq Confidential – Need to Know Required
Writer: Debbie McRill Project: Compaq DAT Drive Reference Guide Comments:
Part Number: 155452-002 File Name: Chapter 1 Overview.doc Last Saved On: 3/14/00 5:01 PM
Projected Duty Cycle
The projected duty cycle of the DAT drive is an important consideration in
determining the amount of time required for backup of a given system as well
as how often it will be necessary to clean the tape drive’s read/write heads.
For example, a nightly, unattended, complete 8-GB backup is well within the
capacity of one 4/8-GB DAT drive. However, at a backup rate between 1
GB/hour and 1.75 GB/hour, that tape drive will be in operation for 6 to 8 hours
every night. With this amount of usage, the tape drive’s read/write heads
should be cleaned
every twelfth night (approximately 100 hours of use)
. If the
drive heads are not cleaned, soft errors and overall backup time will increase
eventually causing the drive to fail. See the section, “Importance of Routine
Cleaning,” in Chapter 4 for more information on cleaning the tape drive.
Cassette Formats
The Compaq DAT drive supports industry-standard Digital Data Storage
(DDS), Digital Data Storage Data Compression (DDS-DC), Digital Data
Storage-2 (DDS-2), Digital Data Storage-3 (DDS-3), and Digital Data
Storage-4 (DDS-4) cassette formats.
DDS-3 tape drives only support DDS-3 cassettes and earlier. DDS-2 tape
drives only support DDS-2 cassettes and earlier.
NOTE:
Only use cassettes purchased from Compaq qualified vendors.
These formats were introduced by the DDS Manufacturers’ Group and are
approved by the American National Standards Institute (ANSI) and the
European Computer Manufacturers’ Association (ECMA). The DDS-DC
format is a superset of the DDS format, ensuring backward compatibility with
uncompressed cassettes.
