z/VM 6.2

Edit online

Version 6.2 of the IBM® z/VM® operating system introduced two concepts that provide the functional foundation for the tests presented in this paper.

  • z/VM Single System Image (SSI)
  • z/VM Live Guest Relocation (LGR)

A z/VM single system image (SSI) cluster is a multi z/VM system environment in which the z/VM systems can be managed as a single resource pool and guests can be moved from one system to another while they are running.

Note: SSI (including the LGR function) is a z/VM 6.2 priced feature that you can order separately.
Note: As of z/VM 6.2 the LGR function is only available for virtual machines running Linux™ for System z® as the guest operating system.

SSI cluster

Edit online

A z/VM SSI cluster consists of up to four z/VM systems in an Inter-System Facility for Communications (ISFC) collection.

Each z/VM system is a member of the SSI cluster. Figure 1 shows the basic structure of a cluster with four members.

Figure 1. A four member z/VM SSI cluster (from IBM z/VM Planning and Administration)

Graph showing 4GiB and 6GiB

The SSI cluster is self-managed by CP using ISFC messages that flow across channel-to-channel devices between the members. All members can access shared DASD volumes, the same Ethernet LAN segments, and the same storage area networks (SANs).

The members of an SSI cluster are connected through ISFC logical links. ISFC logical links are z/VM logical elements defined to the z/VM systems composing the SSI cluster. ISFC logical links in turn are configured to use FICON® CTC (FCTC) devices on FICON channels that connect the logical partitions hosting the z/VM systems.