Incremental Snapshots across disks

Dylan Drudge 20 Reputation points
2024-08-14T18:29:31.8466667+00:00

We've got a use case where I'd like a main disk/snapshot/blob to be able to create other disks from it and have those disk snapshots be incremental off of the main disk state. Currently, from all of my testing creating another disk changes the uniqueFamilyId of the snapshot so when performing the descendant disk snapshots they are full snapshots which is not ideal from a cost perspective.

Is there any way to set the uniqueFamilyId of a snapshot to make the descendant disk snapshots incremental off of that main snapshot? Or is there another way to achieve this tree type of disk diffing we are looking for using blob storage, or something else we may be missing?

Being able to delete and restore a disk and have it preserve its snapshot history would also solve this issue, but it seems everything I have tried always results in a different UUID for the disk itself, resulting in a full copy snapshot after the restoration.

Example scenario:

Main disk snapshot A is created. 10 disks are created from snapshot A and all create their own snapshots. These 10 snapshots ideally would be incremental and form their own nodes in the "tree" and be able to have more snapshots taken over time as the 10 disks continue to diverge from the root node.

Thanks ahead of time!

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  1. Nehruji R 7,306 Reputation points Microsoft Vendor
    2024-08-16T12:58:01.4866667+00:00

    Hello Dylan Drudge,

    Greetings! Welcome to Microsoft Q&A Platform.

    I understand that you’re trying to optimize your snapshot strategy to reduce costs by ensuring that descendant snapshots are incremental rather than full.

    Azure supports incremental snapshots for managed disks. These snapshots only store the changes since the last snapshot, which can significantly reduce storage costs. However, the uniquefamilyid is not something you can set manually. You can identify incremental snapshots from the same disk using the SourceResourceId property. This property links snapshots to their parent disk, allowing you to manage and track them more effectively. However, each new disk created from a snapshot will have a new UUID, which means subsequent snapshots will be full snapshots.

    Snapshots are billed based on the used size. For example, if you create a snapshot of a managed disk with provisioned capacity of 64 GiB and actual used data size of 10 GiB, that snapshot is billed only for the used data size of 10 GiB. You can see the used size of your snapshots by looking at the Azure usage report. For example, if the used data size of a snapshot is 10 GiB, the daily usage report will show 10 GiB/(31 days) = 0.3226 as the consumed quantity.

    For more details on Snapshot refer similar thread - https://video2.skills-academy.com/en-us/answers/questions/796649/queries-related-managed-disks-snapshot

    For unmanaged disks, you can use blob storage snapshots. These snapshots capture the state of a blob at a specific point in time. Incremental snapshots for blobs are supported, and you can use tools like AzCopy to manage these snapshots.

    Custom Backup Strategy: If the built-in snapshot capabilities don’t meet your needs, you might consider implementing a custom backup strategy. This could involve taking periodic snapshots and copying them to another storage account, ensuring that only incremental changes are stored.

    When you delete and restore a disk, the UUID changes, which disrupts the snapshot chain. Unfortunately, Azure does not currently support preserving the UUID of a disk after deletion and restoration.

    Also make sure to read out the restrictions of incremental snap shots https://video2.skills-academy.com/en-us/azure/virtual-machines/disks-incremental-snapshots?tabs=azure-portal#restrictions

    https://video2.skills-academy.com/en-us/azure/virtual-machines/disks-incremental-snapshots Also refer to the Disk Pricing page for questions on cost: https://azure.microsoft.com/en-us/pricing/details/managed-disks/

    Hope this helps! please let us know if you have any further queries. I’m happy to assist you further.

    Please "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.

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