grub2-install fails to install the boot loader on a newly replaced raid member disk.

Solution Verified - Updated -


  • grub2-install fails to write the boot loader on a newly replaced disk used by mdraid with the error:

    grub2-install: error: unknown filesystem.
  • The failure appears randomly, but once it appears, it is persistent until the system is rebooted or caches are dropped (more details in the "Resolution" section)


  • Red Hat Enterprise Linux 7.6 (with grub2-2.02-0.76.el7.1.x86_64)
  • /boot on mdraid with metadata version 1.0

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