Cisco DNCS System Release 2.8.1 3.8.1 4.3.1 User Guide

Consider the following recommendations concerning your tape drives and the tapes that you use for the
database backup.



Use seven tapes (or sets of tapes) for the database backup, one for each day of the week. 

Important: The tapes that you use to back up your Informix database wear out over time. Be sure to
replace your tapes at least once a year.



You can back up your Informix database to either a 4-mm or an 8-mm data tape. The type of tape you

choose depends upon the type of tape drive installed on your DNCS. An 8-mm tape is too big for a 4-mm
tape drive; a 4-mm tape is too small for an 8-mm tape drive. Ask the person who handles your account
if you are not sure which type of tape is appropriate for your system.



You can purchase 4-mm tapes or 8-mm tapes in various lengths. While all tapes wear out over time, a

longer tape is likely to wear out quicker than a shorter tape because the strength of a tape is inversely
proportional to the length of the tape. Use the following guidelines when you purchase tapes to back up
your Informix database:



4-mm tapes: Do not exceed 150 meters



8-mm tapes: Do not exceed 160 meters



Depending on the size of your database, you may need more than one tape to do a complete backup. If

you need more than one tape to back up your database, the backup script will prompt you to remove the
existing tape and to insert a new tape at the appropriate time.



The script used by the DNCS to back up the Informix database uses the following default tape drive

configuration:



Tape size: 5859375 KB



Block size: 16



Device name: /dev/rmt/0h

This tape drive configuration is in use on a majority of systems. Occasionally, the tape drive on a system
may be configured with a different device name, such as /dev/rmt/1h.

Note: The 'h' that appears at the end of device name /dev/rmt/0h or /dev/rmt/1h indicates that the
system is to use a high density format when writing to the tape.