68870: Acronis Cyber Protect: Backup fails with "Failed to create snapshot" on RHEL 8.4, CentOS 8.4 and AlmaLinux 8.4

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Operating Systems: 

Last update: 26-08-2021

Symptoms

Backup of a Linux system with kernel 4.18 fails with the following error:

Failed to create a snapshot

Cause

Kernel 4.18 contains backported changes from kernel 5.8.

Recently, certain low-level block layer changes were backported from Linux kernel series 5.8 to the newer members of the 4.18 kernel series (starting from 4.18.0-305) which causes an incompatibility with the current public release of the snapapi26 kernel module that is used by Acronis products on Linux to implement point-in-time disk snapshots. These backported changes to the block layer make it impossible for the current public snapapi26 module release to attach itself to the kernel and intercept disk reads and writes, which makes point-in-time snapshots impossible,

Most common affected distributions: RHEL 8.4 and 8.3, and derivatives

  • RHEL8.4 (and RHEL 8.3, as that started receiving the new kernel versions as part of its normal update channel).
  • CentOS 8.4 (and CentOS8.3, similarly to the above)
  • OracleLinux 8.4 (and OracleLinux 8.3, similarly to the above) when running the RedHat-compatible kernel 
  • AlmaLinux8.4 (and AlmaLinux8.3,  similarly to the above)
  • RockyLinux

Solution

For Acronis Cyber Protect Cloud and Acronis Cyber Protect 15 (Cloud deployment):

New SnapAPI kernel module compatible with 5.8 and 4.18.0-305(+) kernels is available in Acronis Cyber Protect 21.07, Agent build 27305. Please install the latest build.

For Acronis Cyber Protect 15 (on-premise deployment):

Support for kernel 5.8 is expected in Update 3 of Acronis Cyber Protect 15.

Until then, as a workaround, you can downgrade the kernel to earlier versions.

As long as the earlier 4.18.0-2xx (or earlier) kernel has been preserved on the machine, the administrator can reboot into the old kernel, rerun the Acronis agent installer to let it rebuild and load its current version of snapapi26 into the kernel), and run backups until the permanent solution is available.

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