File system not created yet

Oct 13, 2025 by wbrum.org 125 views

Introduction

Systemd-fsck is a critical service in Qubes OS that ensures the integrity of the file system. However, in some cases, it may fail on the first boot, causing issues with the system's functionality. In this article, we will delve into the issue, explore the possible causes, and discuss potential solutions.

Background

Qubes OS 4.3 is a popular operating system that provides a secure and isolated environment for users. It uses a unique approach to virtualization, allowing users to run multiple virtual machines (VMs) on a single host. The system relies heavily on systemd, a system and service manager for Linux operating systems.

The Issue

When a fresh Qubes OS VM is created and started, the systemd-fsck service may fail to check the file system on the /dev/xvdb device. The error message indicates that the superblock is corrupt, and the file system is not valid. This issue is not unique to Qubes OS, as similar problems have been reported in other Linux distributions.

Steps to Reproduce

To reproduce the issue, follow these steps:

Create a fresh Qubes OS VM using the whonix-workstation-17 template.
Start the VM.
Check the journalctl logs to verify the error.

Expected Behavior

The expected behavior is that the systemd-fsck service should successfully check the file system on the /dev/xvdb device without any errors.

Actual Behavior

The actual behavior is that the systemd-fsck service fails to check the file system on the /dev/xvdb device, resulting in the following error message:

[2025-03-12 21:38:51] [    3.277759] systemd-fsck[362]: fsck.ext2: Bad magic number in super-block while trying to open /dev/xvdb
[2025-03-12 21:38:51] [    3.277925] systemd-fsck[362]: /dev/xvdb:
[2025-03-12 21:38:51] [    3.277964] systemd-fsck[362]: The superblock could not be read or does not describe a valid ext2/ext3/ext4
[2025-03-12 21:38:51] [    3.277999] systemd-fsck[362]: filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
[2025-03-12 21:38:51] [    3.278036] systemd-fsck[362]: filesystem (and not swap or ufs or something else), then the superblock
[2025-03-12 21:38:51] [    3.278057] systemd-fsck[362]: is corrupt, and you might try running e2fsck with an alternate superblock:
[2025-03-12 21:38:51] [    3.278080] systemd-fsck[362]:     e2fsck -b 8193 <device>
[2025-03-12 21:38:51] [    3.278101] systemd-fsck[362]:  or
[2025-03-12 21:38:51] [    3.278122] systemd-fsck[362]:     e2fsck -b 32768 <device>
[2025-03-12 21:38:51] [    3.283801] systemd-fsck[359]: fsck failed with exit status 8.
[2025-03-12 21:38:51] [    3.283899] systemd-fsck[359]: Ignoring error.

Possible Causes

The possible causes of this issue are:

File system not created yet: The file system on the /dev/xvdb device is not created yet, and the systemd-fsck service is trying to check it.
Corrupt superblock: The superblock of the file system on the /dev/xvdb device is corrupt, and the systemd-fsck service is unable to read it.

Potential Solutions

To resolve this issue, the following potential solutions can be considered:

Split qubes-mount-dirs.service: Split the qubes-mount-dirs.service into separate mkfs and mount services, and have fsck between them.
Adjust fsck to be skipped on fresh boot: Adjust the fsck service to be skipped on fresh boot, and only run it when the file system is already created.

Conclusion

Q: What is systemd-fsck@xvdb?

A: Systemd-fsck@xvdb is a service in Qubes OS that checks the file system on the /dev/xvdb device for errors and inconsistencies.

Q: Why does systemd-fsck@xvdb fail on first boot?

A: Systemd-fsck@xvdb may fail on first boot due to a corrupt superblock or because the file system on the /dev/xvdb device is not created yet.

Q: What is a superblock?

A: A superblock is a critical part of a file system that contains metadata about the file system, such as the file system's size, the location of the file system's blocks, and the file system's inode table.

Q: What is an inode table?

A: An inode table is a data structure that contains metadata about the files and directories on a file system, such as the file's permissions, ownership, and timestamps.

Q: Why is the superblock important?

A: The superblock is important because it contains critical metadata about the file system, and if it is corrupt, the file system may not be usable.

Q: How can I fix a corrupt superblock?

A: To fix a corrupt superblock, you can try running the e2fsck command with an alternate superblock, such as:

e2fsck -b 8193 <device>

e2fsck -b 32768 <device>

Q: What is the difference between e2fsck and fsck?

A: E2fsck is a specific tool for checking and repairing ext2 and ext3 file systems, while fsck is a more general tool for checking and repairing file systems.

Q: How can I prevent systemd-fsck@xvdb from failing on first boot?

A: To prevent systemd-fsck@xvdb from failing on first boot, you can try splitting the qubes-mount-dirs.service into separate mkfs and mount services, and have fsck between them.

Q: What is the qubes-mount-dirs.service?

A: The qubes-mount-dirs.service is a service in Qubes OS that initializes and mounts the /rw and /home directories.

Q: Why is the qubes-mount-dirs.service important?

A: The qubes-mount-dirs.service is important because it initializes and mounts the /rw and /home directories, which are critical for the system's functionality.

Q: How can I troubleshoot systemd-fsck@xvdb issues?

A: To troubleshoot systemd-fsck@xvdb issues, you can check the journalctl logs for errors, and try running the e2fsck command with an alternate superblock.

Q: Where can I find more information about systemd-fsck@xvdb?

A: You can find more information about systemd-fsck@xvdb in the Qubes OS documentation and online forums.