Configuring Persistent Memory Devices (PMEM) results in booting to the recovery shell

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Environment

SUSE Linux Enterprise Server 12 Service Pack 4 (SLES 12 SP4)

Situation

Configuring PMEM devices with fsdax namespaces results in the server booting to the recovery shell.

Resolution

Force the libnvdimm module to load after the btrfs kernel module by adding the following entry to for example "/etc/modprobe.d/99-local.conf":

# Load btrfs before libnvdimm
softdep libnvdimm pre: btrfs

Cause

The PMEM device configuration delays the loading of the nvdimm module, which in turn delays the loading of subsequent modules and results in disk timeouts.

Disclaimer

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