Question

Does AHV support creating external snapshots?

  • 12 October 2023
  • 5 replies
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I have a virtual machine that created a snapshot. After logging into the CVM, I can find the disk files corresponding to the snapshot in the snapshot directory. However, the size of the snapshot file is equal to the size of the master disk, which is a complete replication, not generating a new file to store the increment. I added a file to the virtual machine and found that the modification was to the master disk, while the last modification date of the snapshot file did not change.

The underlying layer of AHV uses kvm, which can create an external snapshot through virsh.

Does AHV support creating external incremental snapshots


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5 replies

Userlevel 4
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HI,

How do you access CVM and know the disk files referring to that particular VM? The method you are referring to is NOT SUPPORTED. 

Even if you see the files by browsing the file systems on CVM, these files are only placeholder files, copying these master or increment files are useless and will not work if you try to import to generic KVM.

Now if you want to backup VMs, you can use some export method, or trial backup tools which can export the disk files in the format you require. Like Hycu, Veeam or others etc.

 Please state the use case so someone can can offer the right solution.

“Does AHV support creating external incremental snapshots”  - This is going to supported by backup solutions as mentioned.

 

F>P

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hi ,sl.farhanparkar

 

The SDK of Vmware Essi has a CBT function, which allows incremental data to be returned through the interface after creating a snapshot. This avoids every backup being a complete replication, which I did not find in AHV. KVM has a function to create external snapshots, which can generate a new disk file after creating the snapshot. Only the modifications made after the snapshot are saved, and the master disk is not modified. I observe Nutanix AHV and it seems to be using another mechanism because it uses distributed storage and cannot achieve certain functions of block storage

Userlevel 4
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Hi Quentus,

 

Nutanix AHV is unlike VMware ESXi in many ways, although its based on KVM its purpose build for HCI only. Now Nutanix have similar functionality like CBT for Nutanix AHV, you don’t targets Nutanix AHV for any management, the Management endpoint is always Nutanix Prism. 

All the backup vendors supporting Nutanix AHV do support change block tracking for AHV VMs. These API needs special access afaik and to be part of Technology Alliance.

You can email elevate@nutanix.com.

Are you developing a solution of some sort?

F>P

 

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I am a C # system engineer who currently uses APIs to achieve full backup and restore. I am looking for a solution for incremental backup. I originally planned to write a file comparison myself, but due to the large size of the disk file, the incremental generation of the comparison is too slow.

 

I am installing Nutanix 6.5.4 LTS CE version. You mentioned that Nutanix AHV has CBT based functionality, but I cannot find a printed interface in API 2.0. Is there a printed interface in API 4.0? How to upgrade the API to 4.0 from 2.0?

Userlevel 4
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Hi Quentus,

You can send email to above address, and the team should be able to help you with required access. The APIs are available by default, you need to call v2 or v4 as required.

https://www.nutanix.dev/ site is dedicated for developers.

F>P