1526 - Azure backup and recovery: frequently asked questions – Redstor

Q: Do customers/partners incur Microsoft Azure egress charges as a result of Redstor’s Azure backup snapshots or backup to Redstor's data centres?

A: No. Customers/partners will not incur any egress charges by using Azure VM Pro backup for either snapshots or backup to Redstor’s Storage Platform.

Q: Why are there no egress charges?

A: When a backup is initiated, Redstor uses an Azure compute service in the same Azure region as the backup source to process the data backup requests.

Snapshots use orchestration APIs, and the snapshots never leave the backup source subscription and resource group.

The processed backups are then sent from the compute service to Redstor’s in-region data centre.

Geo-region-Egress Charges 1.png

A: All our snapshots are incremental - the first snapshot is essentially a full snapshot due to the size difference between an incremental delta and zero.

Q: What will it cost to backup my Azure VMs to Redstor's platform?

A: To get the most accurate quote, we recommend starting a free trial and using the estimated charge feature. If this is not ideal, you can get a rough estimate through one of the following options:

Option 1: Run a query on each VM in Azure (free but very slow)

This may require configuration changes and will depend on the target OS.

Option 2: Enable VM Insights in Azure (not free but very efficient)

This will auto-deploy an agent to each configured machine, which will report guest metrics to a Log Analytics workspace of your choice. You can then query this programmatically.

You will need to run the query against a Log Analytics workspace that is connected to VM Insights.

InsightsMetrics
| where Name == "FreeSpaceMB"
| extend Tags = parse_json(Tags)
| extend mountId = tostring(Tags["vm.azm.ms/mountId"])
     ,diskSizeMB = toreal(Tags["vm.azm.ms/diskSizeMB"])
| project-rename FreeSpaceMB = Val
| summarize arg_max(TimeGenerated, *) by Computer, mountId
| extend FreeSpacePercentage = round(FreeSpaceMB / diskSizeMB * 100, 1)
| extend diskSizeGB = round(diskSizeMB / 1024, 1)
     ,FreeSpaceGB = round(FreeSpaceMB / 1024, 1)
| extend UsedDiskSpaceGB = round(diskSizeGB - FreeSpaceGB)
| project TimeGenerated, Computer, mountId, diskSizeGB, FreeSpaceGB, FreeSpacePercentage, UsedDiskSpaceGB
| order by Computer asc, mountId asc

It will then generate a report showing the latest UsedDiskSpaceGB value for each VM and each disk.

You may already have VM Insights enabled across the board. If not, see Microsoft's documentation on how to enable this.

Q: What are the limitations of Redstor Protect?

A: There are some scenarios in which Redstor Protect does not currently offer full support. This list includes, but is not limited to, the following:

storage pools (Azure SQL images are configured to use this for data and log volumes)
RAID configurations that make use of striping
encryption when the keys are customer-managed

Consider disabling Redstor Protect in these scenarios.

Also note that if you are using Redstor Protect for Azure VM Pro, Full System Recovery to any other target is NOT possible. That means if these snapshots are removed, your only option is file and folder restore.

Q: How does authentication work when backing up Azure with Redstor?

A: We rely on Azure service principals. Read more in Article 1412.

Q: When selecting resources (VMs) to protect, is it possible to choose a specific directory?

A: Unfortunately, not yet. Resources are currently shown as a flat list.

Q: What permissions are required to add resources?

VMs can only be added for backup by a user with the Owner role for service principal creation in the relevant subscription.

When the customer adds a resource, Redstor automatically adds the service principal with the relevant app ID to the subscription and gives it the minimum required permissions. The service principal is also linked to Redstor in the backend, using the User_Impersonation Graph API permission, so that this can be used to manage the resource for future operations.

Only the app creation step makes use of User_Impersonation, which is why we have the Owner role requirement for deployment. In terms of permissions, Redstor can only create the same role assignments (to service principals) as the performing user, and access checks are in place for all user-driven read/write operations.

Q: How often do backups run?

A: There is one backup per day per resource.

Q: Does Redstor support the backup of temporary disks on Azure VMs?

A: Temporary disks are not managed disks, so Redstor does not backup these temporary disks in Azure VMs. However, a temporary disk serves as only a cache, so there is no loss in not backing it up. A temporary disk provides short-term storage for processes and applications. It is intended to only store data such as page files, swap files, or the SQL Server tempdb. The only times when data on a temporary disk may be lost are during a maintenance event, or when you redeploy or stop the VM.

Recovery

Q: What are the typical recovery times?

A: Typical recovery times are as follows:

Recovery from Azure snapshot (same VM or new VM): Depending on disk size and count, typically completes in 1-10 minutes.
Recovery from Redstor Platform backup: Restoring via InstantData is typically very rapid (<1min) due to its ability to rehydrate stub files on demand. Full disk rehydration is dependent on disk size and bandwidth.

Q: Does Redstor support Trusted Launch?

A: Yes, Redstor supports recovery of Azure Virtual Machines using the trusted launch security type, which incorporates full support for both Secure Boot and virtual Trusted Platform Module (vTPM).

Q: Does Redstor support the restoring of Azure Virtual Machines with disk type Premium SSD v2?

A: Yes. If the source is set to Premium SSD v2, the restore target will be set to Premium SSD v2 as well.

Page contents

Backup

Recovery

Related articles