Description :
Changes to Arcus NVMeoFC multipath.conf settings for RHEL 8.x/9.x to be included in kernel by default

Arcus added support for ANA (Asymmetric Namespace Access) for NVMeoFC. This is similar to ALUA for SCSI. A change in multipath.conf is required for a RHEL host to take advantage of this and send IO down only ANA optimized paths when available. Without this change, device mapper will send IO down both ANA optimized and ANA non optimized paths.

Here is the change required:

Before Arcus:
    device

{         vendor "NVME"         product "HPE Alletra"         path_grouping_policy multibus         path_selector "service-time 0"         path_checker "none"         prio const         failback immediate         rr_weight uniform         no_path_retry "queue"         rr_min_io_rq 1         fast_io_fail_tmo 10         dev_loss_tmo 14     }

New for Arcus:
    device

{         vendor "NVME"         product "HPE Alletra"         path_grouping_policy "group_by_prio"         path_selector "service-time 0"         path_checker "none"         prio const         failback immediate         rr_weight uniform         no_path_retry "queue"         rr_min_io_rq 1         fast_io_fail_tmo 10         dev_loss_tmo 14     }

After making the above change in /etc/multipath.conf, restart the multipathd service for the change to take effect:

1. systemctl restart multipathd

Notes:
•    This change is for NVMeoFC only. FCP multipath.conf content already had this setting for supporting ALUA previously.
•    The above is an example. If you are using a Merlin surrogate, the product would be "HPE Primera".