How to mount the filesystem when the mount point is a symlink?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 8,9,10
    • EXT4
    • XFS

Issue

Resolution

  • Systemd generates .mount units based on real paths, not symbolic
    links.
  • Avoid using symbolic links as mount points in /etc/fstab across all
    RHEL versions.
  • Use real, canonical directories as mount points

Root Cause

Mounting a filesystem where the target directory is a symlink is not a supported or reliable method. The behavior varies slightly between RHEL versions due to changes in how systemd and mount units handle symlink resolution and canonical paths.

Diagnostic Steps

  • Mount EXT4 and XFS filesystems:
# cat /proc/self/mounts | grep -i /test
/dev/mapper/vg1-lv1 /test1 ext4 rw,seclabel,relatime 0 0
/dev/mapper/vg1-lv2 /test2 xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
  • Create a symlink of EXT4 & XFS mount-point:
# ln -s /test1   /test3
# ln -s /test2 /test4
# ls -l /test3 /test4

lrwxrwxrwx. 1 root root 6 May 28 12:06 /test3 -> /test1
lrwxrwxrwx. 1 root root 6 May 28 12:07 /test4 -> /test2
  • Add entries in fstab.
/dev/mapper/vg1-lv1 /test3 xfs defaults 0 0
/dev/mapper/vg1-lv2 /test4 ext4 defaults 0 0
  • Reboot the system.
  • The filesystem is mounted on the canonical path (/test1 & /test2)
# cat /proc/self/mounts | grep -i /test

/dev/mapper/vg1-lv2 /test2 xfs rw,seclabel,relatime,attr2,inode64,noquota 0 0
/dev/mapper/vg1-lv1 /test1 ext4 rw,seclabel,relatime 0 0

RHEL 8:

May 28 03:04:57 rhel8 systemd[1]: Mounted /test1.
-- Subject: Unit test1.mount has finished start-up
-- Unit test1.mount has finished starting up.
May 28 03:04:57 rhel8 systemd[1]: Mounting /test2...
-- Subject: Unit test2.mount has begun start-up
-- Defined-By: systemd
-- Unit test2.mount has begun starting up.
May 28 03:04:57 rhel8 kernel: XFS (dm-3): Ending clean mount
May 28 03:04:57 rhel8 kernel: XFS (dm-2): Ending clean mount
May 28 03:04:57 rhel8 systemd[1]: Mounted /test1.
-- Subject: Unit test1.mount has finished start-up
-- Unit test1.mount has finished starting up.
May 28 03:04:57 rhel8 kernel: EXT4-fs (dm-4): mounted filesystem with ordered data mode. Opts: (null)
May 28 03:04:57 rhel8 systemd[1]: Mounted /test2.
-- Subject: Unit test2.mount has finished start-up

  • In RHEL 8, mounting a filesystem using a symlink as the mount point in /etc/fstab generally works, but the
    symlink is internally resolved to its real path

  • The mount operation succeeds on the canonical path, and systemd generates the .mount unit based on the actual
    directory, not the symlink

RHEL 9:

May 28 12:52:52 ansihost systemd[1]: Mounting /test1...
░░ Subject: A start job for unit test1.mount has begun execution
░░ A start job for unit test1.mount has begun execution.
May 28 12:52:52 ansihost kernel: XFS (dm-3): Mounting V5 Filesystem 770071cb-c2a1-4361-8cf0-4e2ef15b3ccb

May 28 12:52:52 ansihost systemd[1]: Mounting /test2...
░ Subject: A start job for unit test2.mount has begun execution
May 28 12:52:52 ansihost systemd[1]: Starting File System Check on /dev/disk/by-uuid/07D5-760B...
░░ Subject: A start job for unit systemd-fsck@dev-disk-by\x2duuid-07D5\x2d760B.service has begun execution
May 28 12:52:52 ansihost kernel: XFS (dm-3): Ending clean mount
May 28 12:52:52 ansihost systemd[1]: Mounted /test1.
░░ Subject: A start job for unit test1.mount has finished successfully
░░ A start job for unit test1.mount has finished successfully.
  • Resolves symlink paths to their canonical targets and generates .mount units based on real paths (not symlinks)

RHEL 10:

May 28 12:11:31 RH10 systemd[1]: Mounting test1.mount - /test1...
░░ Subject: A start job for unit test1.mount has begun execution
A start job for unit test1.mount has begun execution.
May 28 12:11:31 RH10 systemd[1]: Mounting test2.mount - /test2...
░░ Subject: A start job for unit test2.mount has begun execution
░░ A start job for unit test2.mount has begun execution.
May 28 12:11:31 RH10 kernel: XFS (dm-2): Mounting V5 Filesystem e5813c74-a288-4bb0-b632-a82bfb99e3de
May 28 12:11:31 RH10 kernel: XFS (vda2): Mounting V5 Filesystem ff7547c1-0c8c-4e31-baa6-9d6a9fd75404
May 28 12:11:31 RH10 kernel: XFS (dm-2): Ending clean mount
May 28 12:11:31 RH10 systemd[1]: Mounted test1.mount - /test1.
░░ Subject: A start job for unit test1.mount has finished successfully
░░ A start job for unit test1.mount has finished successfully.

May 28 12:11:31 RH10 systemd[1]: Mounting test2.mount - /test2...
░░ Subject: A start job for unit test2.mount has begun execution
░░ 
░░ A start job for unit test2.mount has begun execution.
May 28 12:11:31 RH10 kernel: XFS (dm-2): Mounting V5 Filesystem e5813c74-a288-4bb0-b632-a82bfb99e3de
May 28 12:11:31 RH10 kernel: XFS (vda2): Mounting V5 Filesystem ff7547c1-0c8c-4e31-baa6-9d6a9fd75404
May 28 12:11:31 RH10 kernel: XFS (dm-2): Ending clean mount

  • RHEL 10 is more strict with canonical path resolution

  • Systemd mount units are tightly bound to the UUID + real directory path.

  • Even if /test3 & /test4 is specified in /etc/fstab, systemd will mount at /test1 and /test2, based on UUID
    resolution.

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