Deploying an SAP HANA multinode scale-out cluster on FC-connected systems requires the SAP HANA storage connector (fcClient or fcClientMpath). The storage connector is responsible for mounting and unmounting the persistence (data and log) to the SAP HANA worker nodes.
The storage connector also writes SCSI-3 persistent reservations (PRs) to the devices. The Linux sg_persist or mpathpersist command initiates an operation known as I/O fencing, which ensures that only one SAP HANA worker host has simultaneous access to a set of data and log devices.
WIth SAP HANA SP05 Rev 53, SAP released a newer version of the storage connector fcClientMpath, which uses the command mpathpersist rather than sg_persist. The main difference is that mpathpersist puts the reservations on the devices, enabling device paths to be added while the mount process is ongoing, whereas sg_persist puts the reservations on the device paths when mounting the devices. Paths cannot be added during the mount process and a remount is necessary.
To use the fcClientMpath connector:
The keys are added during the mount process to /etc/multipath/prkeys.