676 Computer Service and Repair
The reason for selecting an incremental or differential backup is based on
the amount of time and disk space required for each type of backup. Since the
incremental backup only copies changes from the last incremental backup, there
is less data to copy. This results in a shorter time period required to perform the
backup. A differential backup copies all data changes since the last full backup.
This can require a significant amount of space and time if there is a great number
of days between full backups. These differences may seem insignificant at first,
but when you are talking about the large volumes of data that some corporations
generate, you can be talking about significant periods of time.
Preventive Maintenance
Performing routine maintenance on the PC can help prevent future
problems and improve system performance. Some of the most common but often
overlooked routine maintenance items are listed in this section. Many of the
items can be scheduled to perform automatically.
System Backups
Backups should be performed as part of routine system maintenance. You
may not be able to repair a failed computer system, but you can at least restore
critical data after installing a clean copy of the operating system. If the system
has been configured to perform automatic backups, check if the backups are
being performed. The automatic backup configuration may have been turned
off or has been corrupted. You can verify that the backup job has run at the
scheduled time and that the backup was successful by checking the backup
log. Most backup programs keep a backup log, which is accessible through the
program’s main menu. You should occasionally verify that the data could be read
and restored from the backup tape. If you have installed a patch, however, you
should verify that you could still restore data. Microsoft has many problems with
Monday Tuesday Wednesday Thursday Friday
Monday Tuesday Wednesday Thursday Friday
An incremental backup uses a series of backup media,
one for each incremental backup made
A differential backup uses the same media
for performing each backup
Last Full
Backup
Data
Recovered
Last Full
Backup
Data
Recovered
Figure 15-30.
The incremental
method requires
the complete set of
disks plus the last
full backup to restore
the system data. The
differential method
requires only the last
differential backup
made plus the last
full backup to restore
the system.