Nutanix supports SCSI-3 PR(persistent reservations).
What is SCSI-3 persistent reservations in volume?
SCSI-3 Persistent Reservations (SCSI-3 PR) ar needed for I/O fencing and resolve the problems of using SCSI reservations during a clustered ISCSI Storage. SCSI-3 PR allows access for multiple nodes to a device and at the same time blocks access for alternative nodes paths.
SCSI-3 reservations are persistent across small computer system interface(SCSI) command bus resets and support multiple ways from a host to a disk. just one host will use SCSI-2 reservations with one path. If the necessity arises to block access to a device owning to information integrity considerations, just one host and one path stay active. the requirements for larger clusters, with multiple nodes reading and writing to storage in an exceedingly controlled manner, create SCSI-2 reservations obsolete.
In SCSI-3 PR technology, interference write access is an easy way of removing a registration from a tool. only registered members will have permission to eject the registration of another member. A member desire to eject another member problems a “preempt and abort” command. Ejecting a node is final and atomatic; an ejected node cannot eject another node.
iSCSI uses TCP (typically TCP ports 80,860 and 3260(is the most common port)) for the protocols.