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Asked: 2024-09-24T04:11:14+05:30 In:

How can I resolve the issue of mounting an unknown filesystem type for an LVM2 member on Ubuntu?

I’ve been wrestling with this issue for a while now, and I’m hoping someone here can help me out. So, I recently upgraded my Ubuntu system and decided to try out LVM for managing my disks. I thought I was being smart by grouping my partitions to make things easier. However, I’ve hit a snag that’s got me scratching my head.

After setting everything up, I’m trying to mount a filesystem that I think is part of an LVM2 member, but I keep getting this “unknown filesystem type” error. It’s driving me nuts! I ran `lvscan`, and it shows my logical volumes are there, so I know the LVM setup itself is working, but when I try to mount one of the volumes, that error pops up every single time.

I’ve played around in the terminal a bit, and checking the output of `lsblk` shows the logical volume is recognized, but the filesystem type is listed as unknown. I thought it might be something to do with how I created the filesystems initially, but I was sure I formatted them correctly with ext4. I even tried using `blkid` to check the UUID, and that seems fine too.

On top of that, I considered if there might be something wrong with the LVM configuration or the way I set it up, but I’m not really sure what to look for. Is it possible that the filesystem got messed up during the upgrade? I’ve seen some posts suggesting using `dumpe2fs` to get more information about the filesystem, but I’m a bit hesitant to dive deeper without knowing what I’m doing.

Has anyone else encountered this kind of problem where LVM volumes show up as unknown filesystem types? What steps did you take to troubleshoot or resolve this? I’m all ears for any tricks, commands, or insights you’ve got! I just want to get back to using my system without going bald from pulling my hair out. Any guidance would be greatly appreciated!

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    2 Answers


    1. Your issue with trying to mount a filesystem on LVM2 volumes that are displayed as having an unknown filesystem type is certainly frustrating, but there are several steps you can take to troubleshoot this problem effectively. First, it’s important to verify that the logical volumes in question were indeed formatted with a filesystem before being added to LVM. Use the `lsblk -f` command to check the filesystem type information; if it shows up as “unknown,” it could indicate that the formatting may not have been successful, or it could have been corrupted during the upgrade process. If you suspect corruption, running `dumpe2fs /dev/your-vg/your-lv` could provide more insight into the filesystem’s integrity and metadata, but proceed with caution to avoid data loss.

      If your logical volumes were formatted correctly and are still being recognized as having an unknown filesystem type, the problem could lie with the underlying LVM configuration. Check the relevant LVM configuration files, ensuring that everything is set up correctly. Additionally, you might want to try using `fsck` on the logical volume to check for and attempt repairs on any filesystem inconsistencies. Be sure to unmount the volume first if it’s currently mounted. If these steps do not resolve the issue, consider reformatting the volume, though this will erase any data present. As always, before taking drastic measures, ensure that you have a backup of any critical data that might reside on those volumes.



    2. It sounds like you’re really in a tough spot with this LVM issue! Here are some things you can try that might help:

      • Check if the filesystem is intact: You can run fsck on the logical volume to see if there are any errors. Just make sure it’s unmounted first.
      • View the superblock: Use dumpe2fs /dev/mapper/your_volume_name to check if the filesystem is still there and hasn’t been corrupted.
      • Reformat if necessary: If it turns out the filesystem is really messed up and you’ve got backups, you might need to reformat the volume with mkfs.ext4 /dev/mapper/your_volume_name (make sure you really want to do this, though, because it will erase anything on that volume!).
      • Check your LVM setup: Are you certain you made the logical volumes correctly? You could run lvdisplay to check the details. Also, make sure the LVM is active with lvchange -ay your_volume_name.
      • Kernel support: If you’re using a very new filesystem type or version of ext4, make sure your kernel has the support required for it. Upgrading the kernel could help!
      • Logs are your friends: Look at /var/log/syslog or use dmesg right after you try to mount. Sometimes they’ll show errors or warnings that can clue you in on what’s going wrong.
      • Consider fallback options: If you have important data, consider seeking help from someone with more experience. There are also data recovery tools out there that might help if things are dire.

      Hopefully, one of these tips helps you figure out what’s going wrong! Don’t hesitate to ask more questions if you need clarification on any of this. Good luck!


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