Visara SCON-20L Installation - Manual (Page 17)

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Chapter 2. Planning for Your Install
Determining the number of SCON
Use the SCON Maximum Capability Chart on the previous pages to help in determining the
number of SCON and hardware mixes that will be required to satisfy your requirements.
The minimum number of SCONs that are required is determined by several factors:
• Whether redundant Console Controllers will be used (recommended)
• The number of ESCON cables required to connect to the LPARs defined
• Whether redundant ESCON Directors are being used
• The number of LPARs defined
• The total number of consoles required
A minimum of two consoles, each located on separate SCON should be used for every
critical application. This allows for a SCON to be powered down for routine maintenance
and configuration changes. At least two SCONs should be connected to each LPAR, to
provide these connections.
When directors are used, the overall number of SCONs that would be required may be
greatly reduced. Up to 16 LPARs (host circuits) can be connected through an ESCON
interface for the 22L (with FADS installed) and 25L. Up to 64 LPARs are supported on
the 28L (with FAD) and 48 on the SCON-3074.
When redundant directors are available, two ESCON interfaces may be desired. The
total number of LPAR connections (host circuits) that a 25L can be configured for is 32.
If redundant host circuits (2) are configured between the 25L and each LPAR, the
maximum number of LPARs that could be supported through the configuration of 32
host circuits (16x2), would be 16. Similarly on the 28L the total number of LPAR
connections supported is 128 with two ESCON interfaces, and when using redundant
connections, that number becomes 64. For the SCON-3074 the numbers are 96 and 48.
The total number of LPARs that the SCON can be configured for is determined by the
number of CU images supported by that unit. In planning for the total number, be sure
to include the redundant connections that may be desired, and any additional LPARs
that may be created in the near-term future, that will require connections for consoles.
Take time to fill out the Console Configurations Planning Worksheet found in Appendix
B, or better yet a similar spreadsheet. A software tool, the SCON Configuration Wizard,
can be used to generate this spreadsheet. This can be used to help determine the total
number of consoles needed to satisfy your requirements. It can later be used as a reference
to aid in performing the configuration of the SCON. In determining the console
requirement, remember the following:
• A single coax CUT terminal can communicate with more than one LPAR, but display
only one full LPAR connection on the screen at one time. Thus you may be able to
share a single device to provide the function of multiple consoles.
• The maximum number of sessions per LPAR supported by the SCON is 32. The maximum
number of sessions per ESCON interface supported on the SCON-2XL is 256. The
maximum number of sessions per ESCON interface on the SCON-3074 is 128.