Figuring Out a Backup Plan
It takes time to create and implement a backup and recovery plan. You’ll need to figure out what data needs to be backed up, how often the data should be backed up, and more. To help you create a plan, consider the following:
- How important is the data on your systems? The importance of data can go a long way in helping you determine if you need to back it up-as well as when and how it should be backed up. For critical data, such as a database, you’ll want to have redundant backup sets that extend back for several backup periods. For less important data, such as daily user files, you won’t need such an elaborate backup plan, but you’ll need to back up the data regularly and ensure that the data can be recovered easily.
- What type of information does the data contain? Data that doesn’t seem important to you may be very important to someone else. Thus, the type of information the data contains can help you determine if you need to back up the data-as well as when and how the data should be backed up.
- How often does the data change? The frequency of change can affect your decision on how often the data should be backed up. For example, data that changes daily should be backed up daily.
- How quickly do you need to recover the data? Time is an important factor in creating a backup plan. For critical systems, you may need to get back online swiftly. To do this, you may need to alter your backup plan.
- Do you have the equipment to perform backups? You must have backup hardware to perform backups. To perform timely backups, you may need several backup devices and several sets of backup media. Backup hardware includes tape drives, optical drives, and removable disk drives. Generally, tape drives are less expensive but slower than other types of drives.
- Who will be responsible for the backup and recovery plan? Ideally, someone should be a primary contact for the organization’s backup and recovery plan. This person may also be responsible for performing the actual backup and recovery of data.
- What is the best time to schedule backups? Scheduling backups when system use is as low as possible will speed the backup process. However, you can’t always schedule backups for off-peak hours. So you’ll need to carefully plan when key system data is backed up.
- Do you need to store backups off-site? Storing copies of backup tapes off-site is essential to recovering your systems in the case of a natural disaster. In your off-site storage location, you should also include copies of the software you may need to install to reestablish operational systems.
The Basic Types of Backup
There are many techniques for backing up files. The techniques you use will depend on the type of data you’re backing up, how convenient you want the recovery process to be, and more.
If you view the properties of a file or directory in Windows Explorer, you’ll note an attribute called Archive. This attribute often is used to determine whether a file or directory should be backed up. If the attribute is on, the file or directory may need to be backed up. The basic types of backups you can perform include
- Normal/full backups All files that have been selected are backed up, regardless of the setting of the archive attribute. When a file is backed up, the archive attribute is cleared. If the file is later modified, this attribute is set, which indicates that the file needs to be backed up.
- Copy backups All files that have been selected are backed up, regardless of the setting of the archive attribute. Unlike a normal backup, the archive attribute on files isn’t modified. This allows you to perform other types of backups on the files at a later date.
- Differential backups Designed to create backup copies of files that have changed since the last normal backup. The presence of the archive attribute indicates that the file has been modified and only files with this attribute are backed up. However, the archive attribute on files isn’t modified. This allows you to perform other types of backups on the files at a later date.
- Incremental backups Designed to create backups of files that have changed since the most recent normal or incremental backup. The presence of the archive attribute indicates that the file has been modified and only files with this attribute are backed up. When a file is backed up, the archive attribute is cleared. If the file is later modified, this attribute is set, which indicates that the file needs to be backed up.
- Daily backups Designed to back up files using the modification date on the file itself. If a file has been modified on the same day as the backup, the file will be backed up. This technique doesn’t change the archive attributes of files.
In your backup plan you’ll probably want to perform full backups on a weekly basis and supplement this with daily, differential, or incremental backups. You may also want to create an extended backup set for monthly and quarterly backups that includes additional files that aren’t being backed up regularly.
Tip You’ll often find that weeks or months can go by before anyone notices that a file or data source is missing. This doesn’t mean the file isn’t important. Although some types of data aren’t used often, they’re still needed. So don’t forget that you may also want to create extra sets of backups for monthly or quarterly periods, or both, to ensure that you can recover historical data over time.
Differential and Incremental Backups
The difference between differential and incremental backups is extremely important. To understand the distinction between them, examine Table 14-1. As it shows, with differential backups you back up all the files that have changed since the last full backup (which means that the size of the differential backup grows over time). With incremental backups, you only back up files that have changed since the most recent full or incremental backup (which means the size of the incremental backup is usually much smaller than a full backup).