Information Technology Reference
In-Depth Information
Image Backups vs. File Backups
The need for backups is a given for any computer system, cloud systems especially because
they literally exist because of data. Therefore, making backups of data is one of the most
important processes in IT and should be a big part of an organization's plan as well as budget.
Losing data is the worst-case scenario for any system, especially one being used
for business, so a backup schedule that is close to real time as possible is important.
Performing backups every few seconds would be unrealistic because that would require
massive amounts of storage as well as computing power because of the overhead, not to
mention the costs. Planning the backup methods and technology is part of the business
impact analysis and business continuity planning. During those phases, the recovery time
objective (RTO) and recovery point objective (RPO) must be established based on the kind
of processes and workflows the system will handle.
Recovery Point Objective
The RPO is the maximum acceptable amount of data loss
allowed measured in time. It is simply the age of the data in backup storage that is required
to resume the normal operations of the system after a failure. For example, if the RPO for a
given system is determined to be 15 minutes, then a backup must be taken every 15 minutes
to ensure that if there just happens to be failure resulting in data loss, the amount of data
lost is only a maximum of 15 minutes' worth. So if a system generates 5 MB of data per
minute, it is acceptable for it to lose a maximum of 75 MB of data.
Recovery Time Objective
On the other hand, RTO is the amount of time allowed for
the system to be down or the time before the system can fully function again. It is the time
span between the failure and recovery. Usually, there are multiple RTOs being defined
because different forms of failure have different recovery times, depending on the severity
of the failure. For sure, major failure caused by infrastructure failure or disasters take lon-
ger to recover from compared to simple software crashes or failing hard disks.
These items have to be considered when choosing the correct type of backup. And
along with the different technology used for backup, discussed in Chapter 8, “Hardware
Management,” administrators can fully control the backup and recovery plan of the orga-
nization and aim for the most performance- and cost-efficient solution for the system in
question.
Currently there are two types of backups. Each has its merits and also some downsides,
and we will next discuss both in detail.
File Backups
File backups, or file-based backups, are the traditional kind of backups, the kind most
of us might be used to doing. The process simply involves creating a duplicate of a file or
a whole folder and then placing it in a separate location or a storage medium that can be
easily accessed to restore it when needed. This method of backup is selective and usually
employed for personal files such as videos and MP3 files or really important files that are
few in number, such as photographs, word processor documents, and spreadsheets.
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