How does vSphere handle memory allocation during the instant clone process?
How does vSphere handle memory allocation during the instant clone process?
In vSphere, the instant clone process involves creating a unique memory pool for each child virtual machine using a technique called copy-on-write (COW). Initially, the memory is shared between the parent and the clones. However, as soon as a modification is made to the memory of a clone, a new unique memory page is created for that specific clone. This approach allows for rapid provisioning of virtual machines by leveraging memory and disk sharing while ensuring that changes to memory are isolated to each individual virtual machine.
D. A unique memory pool is created per child virtual machine using copy-on-write. During the instant clone process in vSphere, a unique memory pool is created for each child virtual machine using a technique called copy-on-write (COW). Instant cloning is a feature in VMware vSphere that allows rapid provisioning of virtual machines by leveraging memory and disk sharing. When an instant clone is requested, a "fork" of the parent virtual machine's memory is created for each child virtual machine. Initially, the memory is shared between the parent and the clones. However, as soon as a modification is made to the memory of a clone (e.g., due to an application running in the clone), a new unique memory page is created for that specific clone.
The correct answer is D - A Unique pool... This answer is from UDEMY. https://kb.vmware.com/s/article/2080735 http://www.yellow-bricks.com/2018/05/01/instant-clone-vsphere-67/ https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-853B1E2B-76CE-4240-A654-3806912820EB.html -The Memory is not cloned as this will take time and consume memory. - An Unique pool is created with copy on write
https://blogs.vmware.com/euc/2016/02/horizon-7-view-instant-clone-technology-linked-clone-just-in-time-desktop.html
D is correct answer. When an instant clone is created in vSphere, the memory allocation is handled in a unique way that differs from traditional cloning methods. Rather than creating a new copy of the virtual machine's memory, vSphere leverages a feature called Memory COW (Copy-On-Write) technology to allow multiple virtual machines to share the same memory space. During the instant clone process, a new virtual machine is created with a snapshot of the parent virtual machine's disk state. However, instead of creating a new copy of the virtual machine's memory, the new virtual machine is linked to the parent virtual machine's memory space, which is marked as read-only. As the new virtual machine runs, any writes to memory are redirected to a new memory page, which is then marked as read-write and is unique to that virtual machine. This means that multiple virtual machines can share the same memory space without interfering with each other. This Memory COW technology allows for faster creation of virtual machines and reduced memory usage, as only the memory pages that have been modified need to be stored separately for each virtual machine.
The result of an Instant Clone operation is a virtual machine that is called a destination virtual machine. The processor state, virtual device state, memory state, and disk state of the destination virtual machine are identical to those of the source virtual machine. During an Instant Clone operation, the source virtual machine is stunned for a short period of time, less than 1 second. While the source virtual machine is stunned, a new writable delta disk is generated for each virtual disk and a checkpoint is taken and transferred to the destination virtual machine.
B is correct: "The processor state, virtual device state, memory state, and disk state of the destination virtual machine are identical to those of the source virtual machine. " Source: https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-853B1E2B-76CE-4240-A654-3806912820EB.html
C. An instant clone is a child VM that shares virtual disks and memory with the parent VM in an ongoing manner. https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/performance/cloning-vSphere7-perf.pdf
Answer B is correct. The result of an Instant Clone operation is a new virtual machine that is identical to the source virtual machine. https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-853B1E2B-76CE-4240-A654-3806912820EB.html
I am choosing C. Based on this (dated 2021): https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/performance/cloning-vSphere7-perf.pdf However, based on this(dated 202): https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-853B1E2B-76CE-4240-A654-3806912820EB.html the answer would be "B" Very tricky question the way it is worded.
Copy on Write technique is for linked clones Linked Clone A linked clone is a child VM that shares virtual disks with the parent VM in an ongoing manner. A linked clone is made from a snapshot of the parent and uses snapshot-based delta disks. The child disks employ a copy-on-write (COW) mechanism, in which the virtual disk contains no data in places until copied there by a write. This optimization conserves storage space. https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/performance/cloning-vSphere7-perf.pdf
Seems answer B is correct https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-853B1E2B-76CE-4240-A654-3806912820EB.html
What is the correct answer?
https://blogs.vmware.com/euc/2016/02/horizon-7-view-instant-clone-technology-linked-clone-just-in-time-desktop.html Important fragment from the URL: Note: Copy-on-write, or COW, is an optimization strategy. This means that whenever a task attempts to make a change to the shared information, it should first create a separate (private) copy of that information to prevent its changes from becoming visible to all the other tasks.
Once instantiated, the Instant Clone is an independent VM that starts executing from the exact running state of the sourceVM which enables rapid provisioning of VMs that are immediately available for consumption, unlike traditional full clones. This instant provisioning is made possible by sharing both the memory and disk state of the SourceVM. From a memory standpoint, all Instant Clones will share the same physical memory pages as its SourceVM. This is true even if Transparent Memory Sharing (TPS) is disabled, which is actually really cool (more details will be updated in KB 2080735 for those interested). In other words, TPS is just one of the techniques that Instant Clone can take advantage of but not solely rely on to help deliver maximum memory efficiencies which ultimately enables greater consolidation ratios.
Correct answer B
https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID- 853B1E2B-76CE-4240-A654-3806912820EB.html
B is correct https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID- 853B1E2B-76CE-4240-A654-3806912820EB.html