File system types (ext4, xfs) in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is ext4 in Linux file systems?

ext4 is a widely used Linux file system known for stability, good performance, and support for large files and volumes. It is an improved version of ext3 with features like journaling and extents.

beginner

What is XFS and when is it commonly used?

XFS is a high-performance journaling file system designed for scalability and speed, especially with large files and parallel I/O. It is often used in servers and systems requiring fast data handling.

intermediate

Which file system supports delayed allocation to improve performance: ext4 or XFS?

Both ext4 and XFS support delayed allocation, which helps improve performance by delaying when disk blocks are allocated until data is flushed to disk.

beginner

How does journaling help file systems like ext4 and XFS?

Journaling helps protect data integrity by keeping a log of changes before they are committed to the main file system. This helps recover quickly after crashes or power failures.

intermediate

Which file system is better suited for very large files and why: ext4 or XFS?

XFS is better suited for very large files because it is designed for high scalability and handles large files and parallel I/O more efficiently than ext4.

Which Linux file system is known for high scalability and speed with large files?

A NTFS

B ext3

C FAT32

D XFS

XFS is designed for high performance and scalability, especially with large files.

What feature do ext4 and XFS share to help protect data integrity?

A Journaling

B Compression

C Encryption

D Defragmentation

Both ext4 and XFS use journaling to log changes before writing to disk, protecting data.

Which file system is the default for many Linux distributions due to its balance of performance and stability?

A ext4

B XFS

C Btrfs

D ZFS

ext4 is the default for many Linux distros because it is stable and performs well.

Delayed allocation in file systems helps to:

A Compress files on the fly

B Encrypt files automatically

C Improve performance by delaying disk block allocation

D Prevent file deletion

Delayed allocation postpones disk block assignment to optimize write performance.

Which file system is typically preferred for server environments handling large data loads?

A ext4

B XFS

C FAT32

D exFAT

XFS is preferred in servers for its ability to handle large files and parallel I/O efficiently.

Explain the main differences between ext4 and XFS file systems.

Think about performance, use cases, and features like journaling.

Describe how journaling works and why it is important in file systems like ext4 and XFS.

Consider what happens during a power failure or crash.

Practice

1. Which command is used to create an ext4 file system on a disk partition?

easy

A. format /dev/sdX1

B. mkfs.xfs /dev/sdX1

C. mkfs.ext4 /dev/sdX1

D. diskformat ext4 /dev/sdX1

Solution

1. Step 1: Understand the command for ext4 file system creation

   The command mkfs.ext4 is specifically designed to create ext4 file systems on a given partition.

2. Step 2: Identify the correct usage with device name

   Using mkfs.ext4 /dev/sdX1 formats the partition /dev/sdX1 as ext4.

3. Final Answer:

   mkfs.ext4 /dev/sdX1 -> Option C

4. Quick Check:

   ext4 creation command = mkfs.ext4 [OK]

Hint: ext4 uses mkfs.ext4 command to format partitions [OK]

Common Mistakes:

• Confusing mkfs.xfs with mkfs.ext4
• Using generic format commands not valid in Linux
• Trying to use unsupported commands like diskformat

2. Which of the following is the correct syntax to create an XFS file system on /dev/sdb1?

easy

A. mkfs.ext4 /dev/sdb1

B. mkfs.xfs /dev/sdb1

C. mkfs.xfs -t xfs /dev/sdb1

D. format xfs /dev/sdb1

Solution

1. Step 1: Identify the command for XFS file system creation

   The command mkfs.xfs is the standard way to create an XFS file system on a partition.

2. Step 2: Confirm the correct device usage

   Using mkfs.xfs /dev/sdb1 formats the partition /dev/sdb1 as XFS.

3. Final Answer:

   mkfs.xfs /dev/sdb1 -> Option B

4. Quick Check:

   XFS creation command = mkfs.xfs [OK]

Hint: Use mkfs.xfs for XFS file system creation [OK]

Common Mistakes:

• Using mkfs.ext4 instead of mkfs.xfs
• Trying mkfs.xfs -t xfs which is invalid syntax
• Using Windows-like format commands

3. What will be the output of the command file -s /dev/sdc1 after formatting /dev/sdc1 with ext4?

medium

A. /dev/sdc1: Linux rev 1.0 ext4 filesystem data

B. /dev/sdc1: XFS filesystem data

C. /dev/sdc1: data

D. /dev/sdc1: DOS/MBR boot sector

Solution

1. Step 1: Understand the file command with -s option

   The file -s command reads the device or file to identify its type.

2. Step 2: Recognize the output for ext4 formatted partition

   After formatting with ext4, the output shows Linux rev 1.0 ext4 filesystem data indicating ext4 file system.

3. Final Answer:

   /dev/sdc1: Linux rev 1.0 ext4 filesystem data -> Option A

4. Quick Check:

   file -s on ext4 = ext4 filesystem data [OK]

Hint: file -s shows filesystem type on device [OK]

Common Mistakes:

• Expecting XFS output after ext4 format
• Confusing raw data output with filesystem info
• Assuming DOS/MBR boot sector output on formatted partition

4. You ran mkfs.ext4 /dev/sdd1 but got an error: "device is mounted". What is the best fix?

medium

A. Unmount the device using umount /dev/sdd1 and retry

B. Use mkfs.xfs instead of ext4

C. Reboot the system and run the command again

D. Format a different device without unmounting

Solution

1. Step 1: Understand the error cause

   The error "device is mounted" means the partition is currently in use and cannot be formatted.

2. Step 2: Unmount the device before formatting

   Using umount /dev/sdd1 frees the device so mkfs.ext4 can run successfully.

3. Final Answer:

   Unmount the device using umount /dev/sdd1 and retry -> Option A

4. Quick Check:

   Unmount device before formatting = umount [OK]

Hint: Unmount device before formatting to avoid errors [OK]

Common Mistakes:

• Trying different filesystem without unmounting
• Rebooting unnecessarily instead of unmounting
• Ignoring the mounted status and forcing format

5. You need a file system for a large data server that requires fast write speed and supports files larger than 16TB. Which file system should you choose?

hard

A. ext4

B. NTFS

C. FAT32

D. XFS

Solution

1. Step 1: Analyze file system limits and performance

   ext4 supports large files but has a practical limit around 16TB; XFS supports very large files and is optimized for high-speed writes.

2. Step 2: Match requirements to file system features

   XFS is designed for large data servers with fast write speeds and supports files larger than 16TB, making it the best choice.

3. Final Answer:

   XFS -> Option D

4. Quick Check:

   Large fast files = XFS [OK]

Hint: Choose XFS for large files and fast writes on servers [OK]

Common Mistakes:

• Choosing ext4 without checking file size limits
• Selecting FAT32 which has small file size limits
• Confusing NTFS as a Linux-native file system