Vsphere Study Notes series-Cluster & Resources pool

Cluster

To implement vmotion, DRS, ha, and other functions, exsi hosts must have two or more hosts. How can we determine the hosts on which vmotion and other drifting functions are executed? This introduces the concept of cluster. All vmotion-based functions are implemented on exsi hosts in the cluster, and VMS only drift in the cluster.

After all exsi hosts are added to the cluster, resources such as CPU and memory are pooled into cluster resources, and resources are allocated to the VM by the cluster. Therefore, we can see that in a cluster, exsi hosts and VMS are sorted at the same level, rather than being subordinate to exsi in a non-cluster environment.

It is worth noting that although the cluster controls all resources, it is impossible for the cluster to allocate resources larger than a single exsi host to the VM due to the limitation of a single exsi resource, that is, the maximum number of resources that a VM can use is equal to that of a single exsi host.

It is easy to create a cluster.

Create data center -----> Create cluster -----> join exsi host. The entire process is wizard-oriented and will not be described here.

Resources pool resource pool

When the data center is huge, the concept of resource pool is introduced to restrict resource abuse and prevent service speed from slowing down due to the resource exceeding the cluster's maximum resources. After creating a resource pool, you can set the resources occupied by the pool. the CPU and memory used by the VM in the resource pool will not exceed the value set by the resource pool.

For example, set the resource pool pool1 to 4 GHz and the memory to 8 GB. In pool1, only 8 GB of memory can be used even if 16 GB memory is allocated to the VM.

The advantages of using resource pools are as follows:

1) facilitates the calculation of the remaining resources of the cluster. The calculation method is: total amount-the limit value of each resource pool * Number of VMS

2) prevent resource abuse and ensure that the cluster resources have a controllable margin

Resource pools mainly control CPU and memory resources, such

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Share refers to the normal limit value of the VM;

Reserved refers to the exclusive resources of the resource pool, which are provided to temporary excessive CPU usage (for example, some applications occasionally encounter CPU spikes ), after the reserved resources are allocated, these resources will be occupied even if they are not used by the VM;

Limit refers to the maximum number of VM instances that can exceed the limit.

 

Right-click the cluster, select new resource pool, and click Wizard to complete resource pool creation. Drag the VM into the resource pool.