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2.2 Memory Channel Restrictions
The Memory Channel interconnect is used for cluster communications
between the member systems.
There are currently three versions of the Memory Channel product; Memory
Channel 1, Memory Channel 1.5, and Memory Channel 2. The Memory
Channel 1 and Memory Channel 1.5 products are very similar (the PCI
adapter for both versions is the CCMAA module) and are generally referred
to as MC1 throughout this manual. The Memory Channel 2 product
(CCMAB module) is referred to as MC2.
Ensure that you abide by the following Memory Channel restrictions:
• The DS10, DS20, DS20E, ES40, GS80, GS160, and GS320 systems only
support MC2 hardware.
• If redundant Memory Channel adapters are used with a DS10, they must
be jumpered for 128 MB and not the default of 512 MB.
• If you have redundant MC2 modules on a system jumpered for 512 MB,
you cannot have two MC2 modules on the same PCI bus.
• If a Memory Channel module is installed on an AlphaServer
GS80/160/320 PCI bus, no other modules may be installed on that PCI
bus, not even the standard I/O module.
• The MC1 adapter cannot be cabled to a MC2 adapter.
– Do not use the BC12N link cable with the CCMAB MC2 adapter.
– Do not use the BN39B link cable with the CCMAA MC1 adapter.
• Redundant Memory Channels are supported within a mixed Memory
Channel configuration, as long as MC1 adapters are connected to other
MC1 adapters and MC2 adapters are connected to MC2 adapters.
• A Memory Channel interconnect can use either virtual hub mode (two
member systems connected without a Memory Channel hub) or standard
hub mode (two or more systems connected to a hub). A TruCluster
Server cluster with three or more member systems must be jumpered for
standard hub mode and requires a Memory Channel hub.
• If Memory Channel modules are jumpered for virtual hub mode, all
Memory Channel modules on a system must be jumpered in the same
manner, either virtual hub 0 (VH0) or virtual hub 1 (VH1). You cannot
have one Memory Channel module jumpered for VH0 and another
jumpered for VH1 on the same system.
• The maximum length of an MC1 BC12N link cable is 3 meters (10 feet).
• The maximum length of an MC2 BN39B link cable is 10 meters.
Hardware Requirements and Restrictions 2–3