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Unformatted text preview: ce backup is an expensive process both in terms of the time
taken to complete and the storage space occupied on the backup device, full backup is not
always suggested. To save on backup time and storage space, one can often go for
incremental backup instead of full backup. In this case, only the newly created files or
files that have been changed since the last backup are copied on the backup device from
the on-line secondary storage device at the time of backup. The obvious question is how
to keep track of the newly created and modified files since the last backup. Fortunately,
every file stored in the system contains the date when it was created or last changed, so
the backup software (known as backup utility) can simply compare these dates to those in
its log for taking incremental backup.
Incremental backup is faster than full backup because it needs to create a copy of only the
new and modified files since the last backup. This may actually result in copying of only
a few files out of hundreds of files stored on the on-line secondary storage device.
However, full backup is simpler and a little safer when the data has to be restored back
from the backup device on to the on-line secondary storage device. If you want to restore
a particular file that was lost, you need to search for it at only one place in case of full
backup, whereas in case of incremental backup you need to search for it on several
backups tracing back from the most recent backup till you find the file. Similarly, in the
event of a disk crash, when all the files are lost and need to be restored back on to a new
disk, it is very easy to do this with full backup as compared to incremental backup
because the full backup is a mirror image of the entire disk and can be restored as it is.
Every computer system needs to have a well defined backup policy. The backup policy
for a computer system depends on its nature of usage, types of users, its operating
environment, etc. A backup policy normally decides about the followi...
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- Spring '14