Support for cross-region copy of incremental snapshots

[jamesc]

Resource Provider
Microsoft.Compute

Description of Feature or Work Requested
Support CopyStart of incremental snapshots of managed disks via CLI. The REST API changes introduces a new option called CopyStart for the creationOption for creating snapshots of managed disks.

{ 
  "id": "/subscriptions/sub/resourceGroups/rg1e47ff76-fc12-483f-9c76-4b74673669ef/providers/Microsoft.Compute/disks/slowDisk",    
  "name": "slowDisk"    
  "type": "Microsoft.Compute/snapshots",    
  "location": "westus",    
  "sku": {    
    "name": "Standard_LRS",    
    "tier": "Standard"    
  },    
  "properties": {    
    "osType": "Windows",    
    "creationData": {    
      "createOption": "CopyStart", 
      "sourceResourceId": "/subscriptions/sub/resourceGroups/resg/providers/Microsoft.Compute/snapshots/mySnapshot
    }
  },    
  "tags": {    
    "department": "Development",    
    "project": "ManagedDisks"    
  }   
  "provisioningState": "Pending",  
  "completionPercent": 75 // readonly: ignored on inputs 
}   

Minimum API Version Required

Swagger Link

• DiskRP swagger for 2021-04-01 azure-rest-api-specs#15665
• Azure/azure-rest-api-specs@0f1cd82

Example: https://github.com/rytruong/azure-rest-api-specs/blob/1f561a67f29460998e4ff8020e0691779ff50756/specification/compute/resource-manager/Microsoft.Compute/stable/2021-04-01/examples/CreateASnapshotFromAnExistingSnapshotInDifferentRegion.json

Target Date
Ignite

[yonzhan]

@zhoxing-ms for awareness

[zhoxing-ms]

@jamesc So CLI needs to add a new parameter to support Copy Start, right? Could you provide the design which includes specific commands and parameters that need to be modified?

[evelyn-ys]

May I know what's the difference between "createOption": "CopyStart" and "createOption": "Copy". For current CLI design, we identify createOption smartly from user input. Is it correct that:

• The createOption is Copy if the target location is the same with the source resource's location
• The createOption should be CopyStart if the target location is different from the source resource's location

@jamesc @grizzlytheodore @rytruong Can you help answer?

[vikramd-ms]

Not necessarily. Copy can only be used within the same region. CopyStart can be used when source and target regions are different as well as when they are the same. There are important scenarios (copying across zones, copying from main region to edge location and other way around) where it is necessary to use CopyStart within the same region so CLI should allow it.

[ramankumarlive]

@evelyn-ys you are correct, CLI should smartly use Copy and CopyStart. Here are the different scenarios:

1. Cross-region copy of snapshot: Azure CLI calls DiskRP's Create Snapshot API by specifying createOption=CopyStart, customers dont have to know about it.

        az snapshot create -g MyResourceGroup -n MySnapshot2 --source MySnapshot1  --Region yourTargetRegion
   

2. Create instantaneous snapshot by copying a disk in the same region: This is the current experience when CLI calls DiskRP's create snapshot API by specifying createOption=Copy.

        az snapshot create -g MyResourceGroup -n MySnapshot2 --source MyDisk
   

3. Create snapshot by hard copying a disk to have hardened snapshots on ZRS in the same region. In this case, customers explicitly specify CopyStart as the creation option.

        az snapshot create -g MyResourceGroup -n MySnapshot2 --source MyDisk --CopyStart
   

[evelyn-ys]

Thanks @vikramd-ms @ramankumarlive. So we will autodetect CopyStart for cross-region scenario and provide an extra --copy-start to specify forcibly.

I found that createOption is a shared parameter for az disk create and az snapshot create. Do both az disk create and az snapshot create need to change or only az snapshot create need this?

[vikramd-ms]

CopyStart only applies to snapshots.

[arorasam]

This is a great facility! Few of question about CopyStart:

1. When will this feature be avaialable worldwide as GA ?
2. Any performance numbers how long CreateCopy operation takes to copy first snapshot (which should be full as none exists on the remote region) for Azure Storage pairs?
3. Is this available in any regions right now (Oct 25) to try out, even as preview?

[evelyn-ys]

Hi @arorasam, if you are asking CLI's release date, then it will be 11/02. I believe it's GAed from service side.
Leave other questions to service team @ramankumarlive @vikramd-ms

[ramankumarlive]

@arorasam

#1: We expect to announce the GA of the feature by the end of this month or early March.
#2: We dont have the performance numbers to share now. We can share the number by the end of April 2022.
#3: You can find the list of regions here: https://docs.microsoft.com/en-us/azure/virtual-machines/disks-incremental-snapshots?tabs=azure-cli#restrictions-1

[ramankumarlive]

@arorasam the feature in GA now worldwide.