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1. What is the periodicity of backup? That is, is the backup procedure executed hourly,
daily, weekly, fortnightly, monthly, etc. The periodicity normally depends on the nature
of usage and the criticality of the stored data of a system.
2. Whether to take full or incremental backup? This again depends on the nature of
usage of the system. For example, if a user creates only a few files (say letters) a day, an
incremental backup performed at the end of each day or even once a week may be
sufficient. On the other hand, if a user frequently creates many files, weekly full backups are safer. A compromise that works well for many systems is performing incremental
backups daily and full backups once in a week.
What storage media to use for backup? This is normally decided by the average
volume of data that is backed up every time the backup procedure is executed. Small
backups are normally taken on floppy disks, whereas larger backups are taken on
magnetic tapes. Very large backups may also be taken on disk packs.
4. Who takes backup? This normally depends on the usage environment of computer
systems. Foi example, in case PCs it is the PC user who is normally responsible for
taking the backup of his/her. PC. In case of large computer centres, where a system is
shared by many users, backup is normally the responsibility of the system administrators
of the system. Often backup is an automated procedure in large computer centres, in
which case it is automatically executed at the defined periodicity and the data on hard
disk is automatically backed up on an on-line backup device such as a tape library. In this
case, backup is the responsibility of the system itself.
Where to store the backup media with the backed up data? We just now saw that the
backup device along with the media may be an on-line device such as a tape library. In
this case, the backup media is actually stored very near to the computer system. This is
not acceptable if we need to protect the data against natural calamities. Hence off-line
storage of backup data is always preferred to its on line sto...
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- Spring '14