5.1 Backups and tar

Question 1

There are three different types of backup?

Answer 1

full, incremental, and differential.

Full backups are more reliable and offer complete restoration

Incremental and differential backups include only data that changed since the last full or incremental backup. They are fast and use less disk space. Incremental backups require each previous incremental backup to be present to restore the data.

Question 2

The ______ command is a Linux utility that system
administrators use to create a backup.

_________ takes files we want to back up and creates an archive of them.

Answer 2

The tar command is a Linux utility that system administrators use to create a backup.

tar (tape archive) takes files we want to back up and creates an archive of them.

Question 3

_______ is the industry standard for compression on Unix-like systems.

Answer 3

gzip is the industry standard for compression on Unix-like systems.

Question 4

_______ offers better compression but is much slower than gzip.

Answer 4

bzip2 offers better compression but is much slower than gzip.

Question 5

What is the general syntax of the tar command?

Answer 5

tar [option(s)] [archive_name] [objects_to_archive]

Question 6

cvvf are short form options for _____.

Answer 6

tar

c - stands for create. Always needed when creating an archive.

v - stands for verbose. It will print progress status and useful information as it’s running.

f - stands for create an archive file, followed by the title of the archive.

Question 7

Tar: Best Practices

In order to maintain confidentiality, privacy, and integrity, what are the best practices when using tar?

Answer 7

When creating archives, be sure they are not writable by an untrusted user.

Inspect all data, such as passwords, before writing to an archive.

Monitor backups. tar is vulnerable to DoS attacks.

Pay attention to diagnostic and exit status of tar.

Question 8

What does this commnad do?

tar xvvf my_laptop_backup.tar

Answer 8

Restores data from a backup

x - Extracts the files from the archive and writes them to disk.

vv - Shows information and progress as tar runs

f - specifies the archive file to use.

Question 9

Incremental backups store a list of which files have changed in a snapshot file, with the extension _____.

Answer 9

Incremental backups store a list of which files have changed in a snapshot file, with the extension .snar.

Question 10

What are some of the drawbacks of using incremental backups?

Answer 10

1. Restoring is slower: you must restore the latest
   full backup, plus all the previous incremental backups.
2. There may be a loss of data if a single backup is corrupted.
3. You must verify an archive was created with no errors, using the tar W option.

Question 11

After listing the contents of an incremental backup, what do the following letters indicate:

- **`Y`** 
- **`N`** 
- **`D`**

Answer 11

After listing the contents of an incremental backup, what do the following letters indicate:

- **`Y`** indicates that the file is contained in the `backup.tar` archive. Newly added
- **`N`** indicates that the file was present in the directory at the time the archive was made, but was not added to the `backup.tar` archive because it has not changed since the last backup. Not newly added
- **`D`** indicates the file is a directory.

Question 12

What command would you use to list the contents of an incremental backup?

Answer 12

• tar [name of backup] --incremental

Question 13

What is the difference between a full and incremental backup?

Answer 13

• A full backup saves every file on a hard drive.

- An incremental backup saves only the data that has changed since the last full backup