How many incremental snapshots can be created for a single disk?

Question

I'm interested in the Azure Disk Backup solution. The documentation says: Azure Disk Backup uses incremental snapshots, which are limited to 200 snapshots per disk. And the other documentation says: A total of 500 incremental snapshots can be created for a single disk. Can anyone clarify the following?

Why are these limits different?
What exactly are they limiting, the number of snapshots that exist simultaneously or the number of snapshots that can be created for a single disk?
Assume I have a disk backup policy with an hourly backup frequency and maximum retention (18 days). Will my disk backup job continue to create new snapshots after that disk's total created snapshots exceed the limit (after 21 days)?

Accepted Answer

Hello Maksym Kharchenko2

The limits mentioned in the Azure Disk Backup documentation can be a bit confusing, so let me clarify them for you:

The limit of 200 incremental snapshots per disk is the maximum number of snapshots that can exist simultaneously for a single disk. This means that if you have a disk that has already reached the limit of 200 snapshots, you will need to delete some of the older snapshots before you can create new ones.

The limit of 500 incremental snapshots per disk is the maximum number of snapshots that can be created for a single disk over its lifetime. This means that if you have a disk that has already reached the limit of 500 snapshots, you will not be able to create any more snapshots for that disk.

Regarding your question about the disk backup policy with an hourly backup frequency and maximum retention of 18 days, the backup job will continue to create new snapshots even after the disk's total created snapshots exceed the limit of 500 snapshots. However, once the disk reaches the limit of 500 snapshots, you will not be able to create any more snapshots for that disk, even if the retention period has not expired yet.

It's important to note that these limits apply to incremental snapshots only. If you are using full snapshots, there is no limit to the number of snapshots you can create for a single disk.

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Answer

The 500 limit of incremental snapshots per Azure disk is not over the lifetime of a disk. You can always delete older snapshots of a disk to make room for newer snapshots such that at a given point in time your disks do not hit the max limit of 500 snapshots per disk.

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How many incremental snapshots can be created for a single disk?

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