How to's - Computer Back-up Solutions

Secure and Effective Computer Backup Solutions

Before you can have a secure and effective plan for managing your data, you must incorporate a strategy that includes the following information:

How often should I back up my computer data?

While there is no requirement on how often to back up your computer data, there is one consideration that can help you decide for yourself: The cost of re-creating data that was added or modified since the last backup. Calculate the manpower, lost time and/or sales, and other costs that would be incurred if the file server or workstation crashed right before the next backup was to take place (always assume the worst scenario). If the cost is excessive, the strategy should be adjusted accordingly.

In an ideal environment, one normal computer backup should be performed on workstations every day and servers should be fully backed up more often. Important data files and directories that constantly change may need to be backed up several times a day. Because of time and media constraints, this is not feasible for many environments, so a schedule including Incremental or differential backups must be implemented. For safety reasons, a full backup should always be performed before adding new applications or changing the server configuration.

How much data must be backed up?

The amount of computer data to be backed up is a key determinant of the media rotation strategy you choose. If you are backing up large amounts of data that needs to be retained on media for long periods of time, you will need to select a strategy that is suitable for these requirements.

How long does the data need to be stored?

The amount of time the data needs to be stored is directly related to the media rotation scheme you use. For example, if you use one media and back up every day, your computer backups will never be more than a day old. Since storage media is relatively inexpensive when compared to the value of your data, it is a good idea to periodically back up your system on media not used in the media rotation scheme and store it permanently. You should have at least 3 daily backups, a one-week-old Normal backup and a one-month-old Normal backup.

Which devices am I backing up?

You will need to coordinate times that are suitable to back up different devices.

Should I include more than one system in each job?

When you are setting up jobs for your computer network, you will have to decide if you want to create one job that includes many devices, or a job for each device. The advantages of having one job per device are that you would know immediately which device did not get backed up, if a device is turned off or moved, backups of other devices will not be affected, and when devices are added to the network you can simply set up new jobs for each device. The disadvantage is you have more jobs to keep track of. The advantages of multiple devices per job are that there are fewer jobs to keep track of and create, you know the order in which the data gets backed up and you could make it an overwrite job and thus be able to use the same name for the media and the job. The disadvantage is if any of the devices in the job are not available during the backup, the job will result in a non-normal completion status.

Computer Media Rotation Methods

There are many different media rotation strategies you can use to protect your computer data. They differ mostly by the number of media required and how long the media is kept before it is rotated back into the schedule (backup horizon). It is definitely important to be able to recover files over the short-term. However, it occasionally necessary to be able to recover some files, or even an OS drive in the event of either intrusion or loss of file(s). The one that works the best for you may not be what works best for another site. The basic rotation method includes seven media tapes. Five of these tapes would be used Monday through Friday, each week. The other two tapes would be used on the last day of each month, making the previous day the earliest recovery and two months prior as the oldest recovery day. Citrus Park Computers recommends the seven tape rotation for the minimum backup solution. Additional tapes make the recovery process that much quicker and thorough. ackup Description and Types

The Archive Bit and Backup Types

Whenever a file is created or changed, the O/S activates the “Archive Bit” (or “modified bit”). Some computer backup software uses this bit to determine whether a file has been backed up. Whenever a file has been backed up the software turns this bit “off”, indicating to the computer system that the file has been backed up. If the file is changed again prior to the next Normal or Incremental backup, the bit is turned on again, and will be backed up in the next Normal or Incremental backup. Differential backups include only files that were created or modified since the last Normal backup. When a Differential backup is performed, the archive bit is left intact.

1) Full Backups

Full backups include all of the data on a volume and use a Normal backup. The advantage to this is files are easy to find. Since full computer backups include all data, you don’t have to search through several media to find a file that you need to restore. There is also always a current backup of your entire system on one media or media set. If you should need to restore your entire computer system, all of the most current information is located on the last full backup. The disadvantages to this are redundant backups. Since most of the files on your file server rarely change, each full backup following the first is merely a copy of what has already been backed up. This requires more media. Also, full backups take longer to perform and can be time consuming.

2) Differential Backups

Differential backups include backing up all files since the last Normal backup. The difference between Differential and Incremental backups is that Incremental backups include only the files that have changed since the last Normal or Incremental backup. The advantages to this are that files are easy to find, and there is less time required for backup and restore. The disadvantage of this is redundant backups. All of the files created or modified since the last Incremental backup are included.

3) Incremental Backups

The advantages of incremental backups are the better use of media, and less time required for backup. The disadvantage is that backups are spread across multiple media.

4) Copy Backups

Copy backups include all selected data and do not affect any media rotation scheme (the archive bit is not changed). Copy backups are useful when you need to back up data for a special purpose, back up specific data, perform an additional backup to take off-site or back up data that belongs to a media rotation job without affecting the rotation cycle.

5) Daily Computer Backups

Daily Computer Backups may be performed in addition to the media rotation scheme selected. The Daily Computer Backup method backs up all files with today’s date (created or changed today). The Daily Computer Backup method does not affect the files’ backup status.

6) Working Set Backups

The Working Set backup option allows you to back up computer data that has been created and modified since the last Normal or Incremental computer backup, and to specify to include computer data that has been accessed in the last x days. This option can speed the recovery of a crashed server because you only need to restore the working set backup to get up and running again, and then restore the latest full backup at a later time (if necessary).

The advantage of this is restoring a system backed up with a Working Set strategy requires only the media containing the latest Working Set. The disadvantage is along with all files accessed in the specified time, all of the files created or modified since the last Normal or incremental backup are included on each media, thus creating redundant Working Set backups. In conclusion, data backups are extremely important to the business environment and should be viewed as a necessary element in computer security standards, policies and practices. This solution provides an easy, effective way of backing up computer data, recovering computer data and restoring the company’s most valuable asset – its data.


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