Information Technology Reference
In-Depth Information
The primary purpose of file backups is to make it easy to recover these important files
no matter what happens to your primary hard disks or computer. Because file backups are
selective, they have the added benefit of being faster and much smaller in terms of used disk
space compared to image backups.
Image Backups
The other kind of backup is an image backup, which by definition is an actual bit-to-bit
copy of each sector of the entire hard drive, hence the name. It is basically a backup copy
of the whole hard drive stored as an image file, which includes all the unnecessary files
such as temporary files, caches, junk files, and even malware and viruses.
The basic idea of an image backup is simply to copy each bit on your hard drive into
another drive without regard for files, folders, or any other related concept. Having a backup
image is a true 100 percent backup and can be considered a snapshot of the exact state of
the hard drive at the time the backup was performed.
The real payoff for having an image backup comes when real catastrophe strikes and
your main hard drive is totally lost. In this scenario, you can easily restore to whatever
state you have in your image backup. This includes all installations, settings, and optimiza-
tions. There is no need to reinstall or format anything, which saves a great deal of time.
In this scenario, an image backup was the perfect choice. For organizations running large
data centers that store large amounts of data, with various hard drives being used to store
data only, image backups are not just ideal, they should be mandatory. All of the data from
customers and other sources can be considered important, so a selective backup like file
backup is not ideal because you will back up everything anyway. Also in this case, cost is
likely not a concern.
Image backups are more suitable for catastrophes or to back up machine configuration
and installation tools, especially when there are a lot of machines to be configured in the
same exact way, as in an organization with many employees. It would be tedious to manu-
ally install the OS and other required applications and then configure each application for
each machine or PC. Multiply that by hundreds and the IT department would have an almost
insurmountable task ahead of them. With disk images of the ideal machine, they can work
with batches of PCs at the same time with minimal supervision; intervention is just needed
for the beginning and end of the procedure.
There are also major downsides of using image backups:
For one, they require large amounts of disk space because you are actually making a
copy of the entire disk.
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There is also the factor of time. It takes a long time to do the backup, and it requires
large amounts of bandwidth if you plan to back up to the cloud.
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The resulting image is considered a single file located on a disk or spanning several
disks, the latter more likely because of the file's size. One drawback to this is if just one
of those fragments gets damaged or corrupted, then you are left with one big corrupted
and unusable file and no backup at all. There are ways to prevent this, but it is still a
possible scenario.
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