Prerequisites For Attaching Open Storage To Ibm I Through Vios; Storage Planning; Performance - IBM I VIRTUALIZATION - READ ME FIRST 7-9-2010 Manual

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Select the correct managed server
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In the menu below, expand Configuration, then Virtual Resources
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Click Virtual Network Management
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Use the drop-down menu to create or modify the settings of a VLAN (referred to as a
VSwitch), including which SEA it uses to access the external network

9. Prerequisites for attaching open storage to IBM i through VIOS

9.1. Storage planning

The first storage planning consideration is having enough available capacity in the open storage
subsystem to create the AIX/VIOS LUNs that will be virtualized to IBM i by VIOS. As mentioned
in the supported hardware section (7.1), it is strongly recommended that only Fibre Channel
or SAS physical drives are used to create LUNs for IBM i as a client of VIOS. The reason is
the performance and reliability requirements of IBM i production workloads. For non-I/O-intensive
workloads or nearline storage, SATA or FATA drives may also be used. This recommendation is
not meant to preclude the use of SATA or FATA drives for other clients of VIOS or other host
servers; it applies only to production IBM i workloads.
If the storage subsystem requires a host kit for AIX/VIOS to be installed before attaching LUNs to
these hosts (as is the case with DS5000 and DS4000), that host kit is also required when
virtualizing LUNs to IBM i. Because the LUNs are virtualized by VIOS, they do not have to match
IBM i integrated disk sizes. The technical minimum for any disk unit in IBM i is 160 MB and the
maximum is 2 TB, as measured in VIOS. Actual LUN size will be based on the capacity and
performance requirements of each IBM i virtual client partition.

9.2. Performance

When creating an open storage LUN configuration for IBM i as a client of VIOS, it is crucial to
plan for both capacity and performance. It may seem that because LUNs are virtualized for IBM i
by VIOS instead of being directly connected, the virtualization layer will necessarily add a
significant performance overhead. However, internal IBM performance tests clearly show that the
VIOS layer adds a negligible amount of overhead to each I/O operation. Instead, our tests
demonstrate that when IBM i uses open storage LUNs virtualized by VIOS, performance is
almost entirely determined by the physical and logical configuration of the storage
subsystem.
The IBM Rochester, MN, performance team has run a significant number of tests with IBM i as a
client of VIOS using open storage. The resulting recommendations on configuring both the open
storage and VIOS are available in the latest Performance Capabilities Reference manual (PCRM)
at http://www.ibm.com/systems/i/solutions/perfmgmt/resource.html. Chapter 14.6 focuses on
virtualized storage for IBM i. In most cases, an existing IBM i partition using physical storage will
be migrated to open storage LUNs virtualized by VIOS. The recommended approach here is to
start with the partition's original physical disk configuration; then create a similar setup with the
physical drives in the open storage subsystem on which LUNs are created, while following the
suggestions in the PCRM sections above.
The commonly used SAN disk sizing tool Disk Magic can also be used to model the projected
IBM i performance of different physical and logical drive configurations on supported subsystems.
Work with IBM Techline or your IBM Business Partner for a Disk Magic analysis. The latest
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