Saturday, May 3, 2008

Virtual I/O Server Overview

What is Advanced POWER Virtualization (APV)
 APV – the hardware feature code for POWER5 servers that enables:
Micro-partitioning – fractional CPU entitlements from a shared pool of
processors, beginning at one-tenth of a CPU
Partition Load Manager (PLM) – a policy-based, dynamic CPU and
memory reallocation tool
– Physical disks can be shared as virtual disks to client partitions
Shared Ethernet Adapter (SEA) – A physical adapter or EtherChannel in
a VIO Server can be shared by client partitions. Clients use virtual
Ethernet adapters
 Virtual Ethernet – a LPAR-to-LPAR Virtual LAN within a POWER5 Server
– Does not require the APV feature code

Why Virtual I/O Server?
 POWER5 systems will support more partitions than physical I/O slots
– Each partition still requires a boot disk and network connection, but
now they can be virtual instead of physical
 VIO Server allows partitions to share disk and network adapter resources
– The Fibre Channel or SCSI controllers in the VIO Server can be
accessed using Virtual SCSI controllers in the clients
– A Shared Ethernet Adapter in the VIO Server can be a layer 2 bridge
for virtual Ethernet adapters in the clients
 The VIO Server further enables on demand computing and server

 Virtualizing I/O saves:
– Gbit Ethernet Adapters
– 2 Gbit Fibre Channel Adapters
– PCI slots
– Eventually, IO drawers
– Server frames?
– Floor space?
– Electric, HVAC?
– Ethernet switch ports
– Fibre channel switch ports
– Logistics, scheduling, delays of physical Ethernet, SAN attach
 Some servers run 90% utilization all the time – everyone knows which
 Average utilization in the UNIX server farm is closer to 25%. They don’t
all maximize their use of dedicated I/O devices
 VIO is departure from “new project, new chassis” mindset

Virtual I/O Server Characteristics

 Requires AIX 5.3 and POWER5 hardware with APV feature
 Installed as a special purpose, AIX-based logical partition
 Uses a subset of the AIX Logical Volume Manager and attaches
to traditional storage subsystems
 Inter-partition communication (client-server model) provided via
the POWER Hypervisor
 Clients “see” virtual disks as traditional AIX SCSI hdisks, although
they may be a physical disk or logical volume on the VIO Server
 One physical disk on a VIO server can provide logical volumes for
several client partitions

Virtual Ethernet
 Virtual Ethernet
– Enable inter-lpar communications without a physical adapter
– IEEE-compliant Ethernet programming model
– Implemented through inter-partition, in-memory communication
 VLAN splits up groups of network users on a physical network onto
segments of logical networks
 Virtual switch provides support for multiple (up to 4K) VLANs
– Each partition can connect to multiple networks, through one or more adapters
– VIO server can add VLAN ID tag to the Ethernet frame as appropriate.
Ethernet switch restricts frames to ports that are authorized to receive frames
with specific VLAN ID
 Virtual network can connect to physical network through “routing"
partitions – generally not recommended

Why Multiple VIO Servers?
 Second VIO Server adds extra protection to client LPARS
 Allows two teams to learn VIO setup on single system
 Having Multiple VIO Servers will:
– Provide you Multiple paths to your OS/Data Virtual disks
– Provide you Multiple paths to your network
– Highest superior availability to other virtual I/O solutions
– Allows VIO Server updates without shutting down client LPAR’s


badari said...


Is it possible we can install VIO server itself on SAN disk...

Santosh Gupta said...

Yes, You Can. San should support.

eckertd said...

How would you go about migrating a dedicated-IO LPAR to a server that employs VIOS?

Naresh Kumar said...

Hi Santosh,

Nice work, Keep it up. Your blog is very usefull and lot of information in it .

Can you explain few more concepts of VIO while creating VLPARS.
What is Entitle Capacity if CPU's ?
How do we caluculate to give Virtual CPU valuses in comparing with Physical CPUs?
Is there any Equation to follow while assigning Virtual CPUS?


gdunn said...

Hi Santosh,

thanks in advance. I am glad this blog exists.

Can you explain why I would want to split the SCSI disk bay back plane to support separate boot disk for my dual vio servers? Do I want to do this? why?


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