Inverted iscsi target partitions for RHEL 6.8 guest in esxi 5.5

I have built on an esxi 5.5, 2 nodes HA cluster on RH6.8 that use OpenFiler to create 2 simple partitions for quorum and data (connected to the nodes via iscsi). I am using a gfs2 filesystem on both. I have a problem that I don't understand and that stop the cluster work: while on the first node, I see the disk /dev/sdb associated to the quorum partition and the /dev/sdc associated to the data partition, on node two I see the inversion.

Have someone experienced this issue? I tried the same configuration on esxi 6.5 and it seems that the problem is not present.