Source

RETAIN tip: H195993

Symptom

This issue occurs after installing Hyper-V service on Windows Server 2008 R2 (WS08R2) on System x3950 M2, Type 7233.

The user may be using an IBM System x3950 M2 with more than 64 cores. For example, a 4-node system with 16 Central Processing Units (CPU), each with 6 cores, for a total of 96 cores. WS08R2 will utilize all 96 of those cores. After installing the Hyper-V feature, however, all CPUs above the 64th one will be "gone" from Device Manager and will no longer be seen or used by the Operating System (OS).

This issue occurs because Hyper-V only supports 64 cores (CPUs). WS08R2 is designed to mask any CPUs above the supported number once Hyper-V is installed.

Affected configurations

The system may be any of the following IBM servers:

• System x3850 M2, type 7233, any model
• System x3950 M2, type 7233, any model

The operating system is:

• Microsoft Windows Server 2008 R2 (WS08R2)

This tip is not option specific.

• The system is configured with 96 CPU's.

Workaround

The system x3950 M2 can support up to 96 cores if using 4-nodes configured with 16 x 6-core CPUs. The user should expect to see 32 of those cores "turned off" by the OS after loading Hyper-V.

Additional information

There is no Fix planned at this time.

The hardware requirements for Hyper-V, both the maximums and the minimums, can be reviewed at the following URL:

http://www.microsoft.com/hyper-v-server/en/us/system-requirements.aspx