2 cissp ® Official Study Guide Eighth Edition

Backup Tape Formats
The physical characteristics and the rotation cycle are two factors that a worthwhile 
backup solution should track and manage. The physical characteristics involve the type of 
tape drive in use. This defines the physical wear placed on the media. The rotation cycle is 
the frequency of backups and retention length of protected data. By overseeing these char-
acteristics, you can be assured that valuable data will be retained on serviceable backup 
media. Backup media has a maximum use limit; after thousands of passes through the 
read/write head of a tape drive, the media begins to lose reliability.

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Chapter 18 
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Disaster Recovery Planning
 Disk-to-Disk Backup 
Over the past decade, disk storage has become increasingly inexpensive. With drive capaci-
ties now measured in terabytes, tape and optical media can’t cope with data volume 
requirements anymore. Many enterprises now use disk-to-disk (D2D) backup solutions for 
some portion of their disaster recovery strategy. 
Many backup technologies are designed around the tape paradigm.
Virtual tape librar-
ies (VTL)
support the use of disks with this model by using software to make disk storage 
appear as tapes to backup software. 
One important note: Organizations seeking to adopt an entirely disk-to-disk approach 
must remember to maintain geographical diversity. Some of those disks have to be located 
offsite. Many organizations solve this problem by hiring managed service providers to 
manage remote backup locations. 
As transfer and storage costs come down, cloud-based backup solutions 
are becoming very cost effective. You may wish to consider using such 
a service as an alternative to physically transporting backup tapes to a 
remote location.