Sizing Volume Containers
A volume container is storage space that holds a volume and VM snapshot data associated with that volume.
You can specify the size of the volume container when you create a VM. As snapshot data accumulates, you may need to increase the size of the volume container. You can expand the volume container, but you cannot decrease its size.
The following factors affect the size of a volume container:
- The volume size
- If snapshots are being taken:
- The number of snapshots retained
- How much data changes between snapshots
- Whether DR protection is enabled
Note: The amount of data that changes between snapshots varies for different applications and can have a large impact on what size the volume container should be. In order to properly size a volume container, you must consider the amount of data that your application changes between snapshots.
If you do not take snapshots and do not enable DR protection, the size of the volume container can be the volume size.
If you take snapshots or enable DR protection, the size of the volume container depends largely on the amount of data that is written to the volume between snapshots. This varies for different applications and different RPO values. For a typical case with 10 or fewer DR-retained snapshots and with an additional 3 user-created snapshots:
- For a VM created with a separate boot disk, or for applications that write relatively small amounts of data between snapshots, a reasonable volume-container size is 2.6 times larger than the volume size.
- For applications that write moderate amounts of data between snapshots, a reasonable volume-container size is approximately 3.5 times larger than the volume size.
- For applications that write larger amounts of data between snapshots, the volume-container size must be more than 3.5 times larger than the volume size.
The following is a general formula to calculate the approximate volume container size :
VolContSize = 2 * VolSize + [(# SnapshotsRetained + 1)* SnapshotSize]
Related Topics
Expanding a Volume Container on the everRun System
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