Virtual I/O Server - IBM Power 595 Technical Overview And Introduction

standard and 9000 bytes are supported with Gigabit Ethernet Jumbo Frames. Thus, with the
POWER Hypervisor's virtual Ethernet, you can increase TCP/IP's MTU size to:
65394 (= 65408 - 14 for the header, no CRC) if you do not use VLAN
65390 (= 65408 - 14, four for the VLAN, again no CRC) if you use VLAN
Increasing the MTU size could benefit performance because it can improve the efficiency of
the transport. This is dependant of the communication data requirements of the running
workload.
Note: Virtual Ethernet interfaces can be configured for both dedicated CPU (LPAR) and
shared processor pool (SPLPAR) logical partitions.

3.7 Virtual I/O Server

The Virtual I/O Server is a special purpose partition that allows the sharing of physical
resources between logical partitions to facilitate improvements in server utilization (for
example consolidation). The Virtual I/O Server owns physical resources (SCSI, Fibre
Channel, network adapters, and optical devices) and allows client partitions to access them
through virtual adapter. This can help to reduce the number of physical adapters in the
system.
The Virtual I/O server eliminates the requirement that every partition owns a dedicated
network adapter, disk adapter, and disk drive. OpenSSH is supported for secure remote login
to the Virtual I/O server. The Virtual I/O server also provides a firewall for limiting access by
ports, network services and IP addresses. Figure 3-3 shows an overview of a Virtual I/O
Server configuration.
external network
physical disk
physical disk
Figure 3-3 Architectural view of the Virtual I/O Server
Because the Virtual I/O server is an operating system-based appliance server, redundancy
for physical devices attached to the Virtual I/O Server can be provided by using capabilities
such as Multipath I/O and IEEE 802.3ad Link Aggregation.
Installation of the Virtual I/O Server partition is performed from a special system backup DVD
that is provided to clients with PowerVM Standard and Enterprise editions. This dedicated
software is only for the Virtual I/O Server and is only supported in special Virtual I/O Server
partitions. Two major functions are provided with the Virtual I/O Server: Virtual SCSI and a
Shared Ethernet Adapter.
120
IBM Power 595 Technical Overview and Introduction
Virtual I/O Server
Shared Ethernet
Adapter
physical virtual Ethernet
Ethernet adapter adapter
physical disk virtual SCSI
adapter adapter
Hypervisor Virtual I/O client 1
virtual Ethernet
adapter
virtual SCSI
adapter
Virtual I/O client 2
virtual Ethernet
adapter
virtual SCSI
adapter