CompTIA Security_ Deluxe Study Guide_ SY0-201 - Emmett Dulaney [212]
Almost every stable operating system contains a utility for creating a copy of configuration settings necessary to reach the present state after a disaster. In Windows Vista, for example, this is accomplished with an Automated System Recovery (ASR) disk. Make certain you know how to do an equivalent operation for the operating system you are running.
As an administrator, you must know how to do backups and be familiar with all the options available to you.
Developing a Backup Plan
Several common models are used in designing backup plans. Each has its own advantages and disadvantages. Numerous methods have been developed to deal with archival backup; most of them are evolutions of the three models discussed here:
Grandfather, Father, Son method The Grandfather, Father, Son method is based on the philosophy that a full backup should occur at regular intervals, such as monthly or weekly. This method assumes that the most recent backup after the full backup is the son. As newer backups are made, the son becomes the father, and the father, in turn, becomes the grandfather. At the end of each month, a full backup is performed on all systems. This backup is stored in an offsite facility for a period of one year. Each monthly backup replaces the monthly backup from the previous year. Weekly or daily incremental backups are performed and stored until the next full backup occurs. This full backup is then stored offsite and the weekly or daily backup tapes are reused (the January 1 incremental backup is used on February 1, and so on).
This method ensures that in the event of a loss, the full backup from the end of the last month and the daily backups can be used to restore information to the last day. Figure 8.4 illustrates this concept: The annual backup is referred to as the grandfather, the monthly backup is the father, and the weekly backup is the son. The last backup of the month becomes the archived backup for that month. The last backup of the year becomes the annual backup for the year. Annual backups are usually archived; this allows an organization to have backups available for several years and minimizes the likelihood of data loss. It’s a common practice for an organization to keep a minimum of seven years in archives.
FIGURE 8.4 Grandfather, Father, Son backup method
The last full backup of the year is permanently retained. This ensures that previous years’ information can be recovered if it’s needed for some reason.
The major difficulty with this process is that a large number of tapes are constantly flowing between the storage facility and the computer center. In addition, cataloging daily and weekly backups can be complicated. It can become difficult to determine which files have been backed up and where they’re stored.
Full Archival method The Full Archival method works on the assumption that any information created on any system is stored forever. All backups are kept indefinitely using some form of backup media. In short, all full backups, all incremental backups, and any other backups are permanently kept somewhere.
This method effectively eliminates the potential for loss of data. Everything that is created on any computer is backed up forever. Figure 8.5 illustrates this method. As you can see, the number of copies of the backup media can quickly overwhelm your storage capabilities. Some organizations that have tried to do this have needed entire warehouses to contain their archival backups.
FIGURE 8.5 Full Archival backup method
Think about the number of files your organization has: How much storage media would be required to accomplish full archiving? The other major problem involves keeping