The real CPUs of the Server Unit x86 are distributed to groups of CPUs, which are known as CPU pools. Each real CPU can be assigned to at most one CPU pool.
One main objective of this distribution to different CPU pools is to seal off the carrier system from the other systems and to separate the Native BS2000 system (or the BS2000 guest systems) from the XenVM guest systems. For the operation of BS2000 this ensures a stable performance in accordance with the SE server model.
A virtual machine (VM) is assigned permanently to a CPU pool in accordance with the VM type (BS2000 VM or XenVM) when it is generated. It can use only the CPUs from this CPU pool, even if CPUs in parallel CPU pools are unused. The scheduling of CPU performance always relates only to the CPUs of a particular CPU pool. The weightings between individual VMs (via limitation and weight) in a CPU pool can thus not influence the weightings among the VMs in another CPU pool.
The distribution of the real CPUs to CPU pools is implemented automatically on the basis of the installed hardware and the installed licenses when the Server Unit x86 is started up and cannot be changed by the user. The CPU pools can be extended by integrating further hardware or by installing further licenses.
The BS2000 CPUs, i.e. those CPUs which are used by the BS2000 systems in accordance with the server model, can be split into further CPU pools using VM2000 means.
The hardware and licenses are installed by Customer Support, and this requires a maintenance window.
In normal operation the CPU pools are configured and managed as follows:
Pool 0
This pool is reserved exclusively for the X2000 basic system. It contains a quarter of the existing real CPUs, but at least 2 CPUs.BS2000 pools
The standard pool is used exclusively by the Native BS2000 system or by the BS2000 VMs. Provided no further BS2000 CPU pools are configured, this pool contains all the BS2000 CPUs.
When further CPU pools are configured with VM2000 means, the BS2000 CPUs can be displayed in other BS2000 CPU pools. The standard pool is retained in this case, but may possibly no longer contain CPUs. BS2000 VMs are assigned to one of these CPU pools when they are created. In ongoing operation, VM2000 means can be used to switch them dynamically between these pools.Linux/Windows pool
This pool exists only if a XenVM license is installed and when sufficient CPUs are available. It is used exclusively by XenVMs.Depending on the hardware and licenses which are installed, further unused real CPUs can exist in the Server Unit outside the pools, the so-called free CPUs.
The CPU pools are also visible under VM2000, but the naming of static pools is retained in VM2000 for compatibility reasons. The table below shows the names of the CPU pools in the X2000 basic system and the names in VM2000.
CPU pool | Users | Name in X2000 | Name in VM2000 |
Pool 0 | X2000 | Pool 0 | *POOL0 |
Standard BS2000 pool | BS2000 | bs2_pool | *STDPOOL |
Pool configured in VM2000 | BS2000 | <name 1..8> | <name 1..8> |
Linux/Windows pool | XenVM | lw_pool | *FOREIGN |
Free CPUs (not a pool) |
Table 3: Overview of the CPU pools (X2000 and VM2000 views)
1For CPUs which are not attached. These are as a rule the CoD CPUs (which are called extra CPUs in VM2000)
In normal operation enough CPUs are available for every pool. A lack of CPUs can occur in the following exceptional situations:
Reduced operation: a hardware failure means that fewer CPUs are operational at system startup.
Abnormal operation: a change of license means that more CPUs are required.
In the case of reduced or abnormal operation the basic system automatically reacts with the following step-by-step measures to rectify the lack of CPUs:
The (free) CPUs not used so far are used
Step-by-step reduction of the Linux/Windows pool to 2 CPUs
The BS2000 CoD CPUs are omitted
Alternating omission of one CPU of the BS2000 pool down to 2 CPUs
Pool 0 is reduced to 1 CPU
The last but one CPU of the Linux/Windows pool and of the BS2000 pool is omitted
Cancelation of the Linux/Windows pool
The SE Manager displays an overview over the available BS2000 CPU pools (including empty pools) and an overview over the BS2000 VMs to which a CPU pool is currently allocated under Systems -> [ <se server>(SE<model>) -> ] <su-name> (model) -> Virtual machines [ -> BS2000] -> VM resources.
For information on BS2000 and BS2000 VMs, see also section "Working in Native BS2000 mode" and section "Working in VM2000 mode", and for information on XenVMs, see also section "Working in XenVM mode (on Server Unit x86)" .