PERFORMING A NORMAL BACKUP EVERY NIGHT ENABLES YOU TO RESTORE THEENTIRE SYSTEM USING ONLY A SINGLE NIGHT’S BACKUP TAPE

5.

Correct Answers: E

A. Incorrect:

Performing a normal backup every night enables you to restore the

entire system using only a single night’s backup tape. However, it uses more tape

backup media than is necessary because every file on the system is backed up

every night.

B. Incorrect:

The incremental backup makes a copy of all files marked with the

archive attribute. After each file has been backed up, the file’s archive attribute is

cleared. Therefore, the incremental backup copies only files that were modified

since the last backup. Performing only incremental backups would require restor-

ing every single backup ever made in the event of a hard disk failure.

C. Incorrect:

The differential backup makes a copy of all files marked with the

archive attribute. Unlike the incremental backup, the differential backup does not

modify the archive attribute of files after creating the backup. In this way, per-

forming a differential backup every night ensures that every file modified since the

last full backup can be restored. This is useful when combined with a normal

backup, but using only differential backups results in a backup set that grows

larger every night. Therefore, the differential backup does not meet the criteria of

minimizing the backup media used.

D. Incorrect:

This is a common backup strategy, but it does not meet the require-

ment of needing to restore only two sets of backups for a complete system recov-

ery. Each incremental backup copies only those files that were modified since the

prior night’s backup. Therefore, every single incremental backup since the last

normal backup must be restored to ensure total data recovery. For example, if a

normal backup was performed on a Sunday and incremental backups thereafter,

restoring the system on Thursday requires restoring Sunday’s normal backup and

Monday’s, Tuesday’s, and Wednesday’s incremental backups.

E. Correct:

This backup strategy meets all the requirements. Differential backups

copy all files modified since the last normal backup, enabling a maximum of two

separate restores to completely rebuild a file system. For example, if a normal

backup was performed on a Sunday and differential backups thereafter, restoring

the system on Thursday requires restoring only Sunday’s normal backup and

Wednesday’s differential backup.