Hyper-v vm memory technology (I)

After the memory is allocated to the virtual machine, the Hyper-V host allocates the available memory resources of the system to the created virtual machine. The default memory is called static memory, that is, when you create a virtual machine, how much GB of memory is allocated to the virtual machine. The dynamic memory function provided by Windows Server 2012 Hyper-V allows the Administrator to re-adjust resources, make full use of limited memory resources to achieve better memory integration and higher management efficiency.

I. Static Memory: the memory allocated to the virtual machine. When a VM is not started, it does not occupy the memory of the physical computer. When the VM is started, the memory of the physical computer is allocated to the VM, the physical computer will reduce memory of the same size .)

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Ii. dynamic memory:

1. Technical Overview: The "dynamic memory" introduced in Windows Server 2008 R2 Service Pack 1 (SP1) defines the startup memory as the minimum memory size of the virtual machine. However, Windows requires more memory during startup than in a stable State. Therefore, administrators sometimes allocate additional memory to virtual machines because Hyper-V cannot reclaim memory from these virtual machines after startup. In Windows Server 2012, "dynamic memory" introduces the Minimum Memory settings to allow Hyper-V to reclaim unused memory from the virtual machine. This is reflected in the increased number of Virtual Machine mergers, especially in the virtual desktop infrastructure (VDI) environment. Windows Server 2012 also introduces the "smart paging" Technology for reliable VM restart operations. Although the minimum memory can increase the number of virtual machines merged, it also brings a challenge. If a virtual machine has a smaller amount of memory than its startup memory, if it restarts, Hyper-V needs additional memory to restart the virtual machine. Due to host memory pressure or virtual machine status, Hyper-V may not always have additional memory available. This may occasionally cause a failure to restart the virtual machine. "Smart paging" is used to bridge the gap between the minimum memory and the startup memory, so that the virtual machine can be restarted reliably.

2. Configure dynamic memory: This example uses the name "VMM-WDS-01" virtual machine as an example to demonstrate how to enable and configure the virtual machine:

Step 1: Open the Server Manager, click tools, and select Hyper-V manager. Right-click the virtual machine that needs to enable dynamic memory, select "set" to display the Virtual Machine Properties dialog box, select "hardware"-"Memory ")

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Step 2: Select "Enable dynamic memory" and configure the maximum and minimum memory values you need to configure. In this example, the minimum memory size is 512 MB, and the maximum is 8192 MB, the default value of the memory buffer is "20% ". The Microsoft buffer percentage ranges from 5% to 95%. Set the Virtual Machine "memory weight" and drag the slider in the "memory weight" area to change the virtual machine memory. When the physical memory is limited, this setting helps determine that the device uses the memory preferentially. This setting means that when the memory is insufficient, the memory will be preferentially obtained if the value is large, the memory of a low-priority VM is denied by the system and then allocated to a higher-priority VM .)

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Step 3: Click OK to start the dynamic memory function.

Step 4: dynamic memory monitoring:

1) enable "Resource Monitor". The memory usage before running the VM is 3633 MB .)

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2) After the VM is running, the VM management window displays the VM memory usage status.) dynamic memory is used to automatically allocate the used memory.

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3) at this time, you will find that the "memory in use" is 4096 MB before the VM runs, and the memory allocated to the VM is MB. After the VM is started, the memory in use is 4303 MB (), and the actual memory used by the VM is 670 MB, which is far lower than the allocated memory, therefore, in the current Hyper-V host, we can run more virtual machines to better meet the usage needs of virtual machines for burst memory and improve memory usage efficiency.

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4) because we use the dynamic memory technology, the usage of VM resources is dynamically changing, and the memory usage is also dynamically changing .)

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In the next article, we will discuss some terms related to Hyper-v vm memory technology.

 

 

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