Multi Pathing in RedHat and SuSE CEPH
There are two major commercial CEPH distributions, RedHat and SuSE. As of July 2019, both differ in how their Multi Pathing works when connected to VMware.
SuSE supports active-active iSCSI gateway deployment. So in vCenter all paths to SuSE Enterprise Storage (SES) CEPH show as ‘active (IO)’. So in the case of SuSE CEPH, we recommend the Round Robin Path Selection Policy (VNX_PSP_RR) in VirtuCache/VMware.
RedHat CEPH does NOT support active-active iSCSI gateway deployment. RedHat supports ALUA – Active-(Optimized) / Active(Unoptimized) mode. So in the case of RedHat, only one path is shown as ‘active (IO)’. So in the case of RedHat CEPH, we recommend the Most Recently Used (MRU) Path Selection Policy (VNX_PSP_MRU) in VirtuCache/VMware.
However it looks like, by the end of 2019, SuSE CEPH might be converting to the Active-(Optimized) / Active(Unoptimized) mode as well, in which case ESXi should be configured with VNX_PSP_MRU PSP for SuSE CEPH as well.