I am getting many of these messages on one of my systems:

[  348.515157] EXT4-fs (vda9): VFS: Can't find ext4 filesystem
[  348.517587] EXT4-fs (vda9): VFS: Can't find ext4 filesystem
[  348.519944] EXT4-fs (vda9): VFS: Can't find ext4 filesystem
[  348.522487] squashfs: SQUASHFS error: Can't find a SQUASHFS superblock on vda9
[  348.524974] FAT-fs (vda9): bogus number of reserved sectors
[  348.525946] FAT-fs (vda9): Can't find a valid FAT filesystem
[  348.533493] XFS (vda9): Invalid superblock magic number
[  348.536738] FAT-fs (vda9): bogus number of reserved sectors
[  348.537781] FAT-fs (vda9): Can't find a valid FAT filesystem
[  348.543638] VFS: Can't find a Minix filesystem V1 | V2 | V3 on device vda9.
[  348.546068] hfsplus: unable to find HFS+ superblock
[  348.547531] qnx4: no qnx4 filesystem (no root dir).
[  348.549902] ufs: You didn't specify the type of your ufs filesystem

               mount -t ufs -o ufstype=sun|sunx86|44bsd|ufs2|5xbsd|old|hp|nextstep|nextstep-cd|openstep ...

               >>>WARNING<<< Wrong ufstype may corrupt your filesystem, default is ufstype=old
[  348.557643] ufs: ufs_fill_super(): bad magic number
[  348.561613] hfs: can't find a HFS filesystem on dev vda9

The disk looks like this:

Model: Virtio Block Device (virtblk)
Disk /dev/vda: 6001GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name                  Flags
 1      1049kB  6001GB  6001GB  zfs          zfs-5514fd574fd36816
 9      6001GB  6001GB  8389kB

It is a Ubuntu-VM with VirtIO disk on a KVM/Qemu system (Proxmox). It works fine but I do not understand whats happening here.

How can I fix this? Thank you!

  • 2
    How are you mounting it? You don't appear to be telling the OS its a ZFS disk / the OS isn't checking if it is a ZFS disk. – symcbean Jan 10 '18 at 13:43
  • I created it with zpool create and zfs create. The system mounts it by it self – Kaai Kivi Jan 10 '18 at 13:59

Those messages are normally generated by mount attempting to guess the filesystem type when mounting. The -t option to specify a filesystem type is optional and if it's not specified, mount will attempt to determine the type automatically.

In your case, something is mounting or attempting to mount vda9 without specifying a filesystem type. As you're using ZFS and looking at the size and position of the partition I'm guessing vda9 is the spare partition that ZFS automatically creates when given a whole disk. I'm not sure why something is trying to mount it, but the messages you've pasted above are purely informational and can safely be ignored - I'd only be concerned if you were getting hundreds of them a day and they were clogging up your log files.

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