Backups are copies of data created to ensure that when the original data is lost or corrupted, it can be restored. If you’re planning to take the SY0-501 exam, you should have a good understanding of backup utilities that support several different types of backups. Even though third-party backup programs can be quite sophisticated in what they do and how they do it, you should have a solid understanding of the basics.
For example, can you answer this practice test question?
Q. Your backup policy for a database server dictates that the amount of time needed to perform backups should be minimized. Which of the following backup plans would BEST meet this need?
A. Full backups on Sunday and full backups on the other six days of the week
B. Full backups on Sunday and differential backups on the other six days of the week
C. Full backups on Sunday and incremental backups on the other six days of the week
D. Differential backups on Sunday and incremental backups on the other six days of the week
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation are available at the end of this post. Each of the eleven chapters presents topics in an easy to understand manner and includes real-world examples of security principles in action. You’ll understand the important and relevant security topics for the Security+ exam, without being overloaded with unnecessary details. Additionally, each chapter includes a comprehensive review section to help you focus on what’s important. Over 300 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes: Each practice test question includes a detailed explanation to help you understand the content and the reasoning behind the question. You’ll be ready to take and pass the exam the first time you take it. If you plan to pursue any of the advanced security certifications, this guide will also help you lay a solid foundation of security knowledge. Learn this material, and you’ll be a step ahead for other exams. This SY0-601 study guide is for any IT or security professional interested in advancing in their field, and a must-read for anyone striving to master the basics of IT security.The 601 Version of the Study Guide
The CompTIA Security+: Get Certified Get Ahead: SY0-601 Study Guide is an update to the top-selling SY0-201, SY0-301, SY0-401, and SY0-501 study guides, which have helped thousands of readers pass the exam the first time they took it. It includes the same elements readers raved about in the previous four versions.
Full Backups
A full backup backs up all data specified in the backup. For example, you could have several folders on the D: drive. If you specify these folders in the backup program, the backup program backs up all the data in these folders.
Although it’s possible to do a full backup on a daily basis, it’s rare to do so in most production environments. This is because of two limiting factors:
- Time. A full backup can take several hours to complete and can interfere with operations. However, administrators don’t always have unlimited time to do backups and other system maintenance. For example, if a system is online 24/7, administrators might need to limit the amount of time for full backups to early Sunday morning to minimize the impact on users.
- Money. Backups need to be stored on some type of media, such as tape or hard drives. Performing full backups every day requires more media, and the cost can be prohibitive. Instead, organizations often combine full backups with differential or incremental backups.
However, every backup strategy must start with a full backup.
Restoring a Full Backup
A full backup is the easiest and quickest to restore. You only need to restore the single full backup and you’re done. If you store backups on tapes, you only need to restore a single tape. However, most organizations need to balance time and money and use either a full/differential or a full/incremental backup strategy.
Differential Backups
A differential backup strategy starts with a full backup. After the full backup, differential backups back up data that has changed or is different since the last full backup.
For example, a full/differential strategy could start with a full backup on Sunday night. On Monday night, a differential backup would back up all files that changed since the last full backup on Sunday. On Tuesday night, the differential backup would again back up all the files that changed since the last full backup. This repeats until Sunday, when another full backup starts the process again. As the week progresses, the differential backup steadily grows in size.
Order of Restoration for a Full/Differential Backup Set
Assume for a moment that each of the backups was stored on different tapes. If the system crashed on Wednesday morning, how many tapes would you need to recover the data?
The answer is two. You would first recover the full backup from Sunday. Because the differential backup on Tuesday night includes all the files that changed after the last full backup, you would restore that tape to restore all the changes up to Tuesday night.
Incremental Backups
An incremental backup strategy also starts with a full backup. After the full backup, incremental backups then back up data that has changed since the last backup. This includes either the last full backup, or the last incremental backup.
As an example, a full/incremental strategy could start with a full backup on Sunday night. On Monday night, an incremental backup would back up all the files that changed since the last full backup. On Tuesday night, the incremental backup would back up all the files that changed since the incremental backup on Monday night. Similarly, the Wednesday night backup would back up all files that changed since the last incremental backup on Tuesday night. This repeats until Sunday when another full backup starts the process again. As the week progresses, the incremental backups stay about the same size.
Order of Restoration for a Full/Incremental Backup Set
Assume for a moment that each of the backups were stored on different tapes. If the system crashed on Thursday morning, how many tapes would you need to recover the data?
The answer is four. You would first need to recover the full backup from Sunday. Because the incremental backups would be backing up different data each day of the week, each of the incremental backups must be restored—and must be restored in chronological order.
Sometimes, people mistakenly think the last incremental backup would have all the relevant data. Although it might have some relevant data, it doesn’t have everything.
As an example, imagine you worked on a single project file each day of the week, and the system crashed on Thursday morning. In this scenario, the last incremental backup would hold the most recent copy of this file. However, what if you compiled a report every Monday but didn’t touch it again until the following Monday? Only the incremental backup from Monday would include the most recent copy. An incremental backup from Wednesday night or another day of the week wouldn’t include the report.
Q. Your backup policy for a database server dictates that the amount of time needed to perform backups should be minimized. Which of the following backup plans would BEST meet this need?
A. Full backups on Sunday and full backups on the other six days of the week
B. Full backups on Sunday and differential backups on the other six days of the week
C. Full backups on Sunday and incremental backups on the other six days of the week
D. Differential backups on Sunday and incremental backups on the other six days of the week
Answer is C. A full/incremental backup strategy is the best option with one full backup on one day and incremental backups on the other days. The incremental backups will take a relatively short time compared with the other methods.
A full backup every day would require the most time every day.
Differential backups become steadily larger as the week progresses and take more time to back up than incremental backups.
Backups must start with a full backup, so a differential/incremental backup strategy is not possible.
See Chapter 9 of the CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide for more information on protecting data.
