The Backup (Backup and Restore) Migration method utilizes backup functionality to first back up source data to the SCMT. The system is then restored to the target virtual machine using the backup files stored on the platform. Compared to Point-to-Point Migration and Hot Standby Migration, this method involves a longer service downtime.

Applicable Scenarios

This approach is primarily used in scenarios where the source data volume is exceptionally large, and the available bandwidth to the target is relatively low, making the required data transfer duration unacceptable. It allows for performing a full backup locally using a migration platform appliance deployed in the high-bandwidth source environment. The appliance can then be physically moved to the target location to perform an incremental backup before final restoration, thereby completing the migration.

Migration Process

The migration process of the backup migration mode in SCMT is as follows:

The source host installs the migration agent, and the migration tool has two modes: active and passive.

• In the active mode, the migration agent at the source actively connects to the SCMT and receives tasks issued by the SCMT.

• In the passive mode, SCMT will take the initiative to connect the source machine migration agent to issue migration tasks.

Perform a full backup of the source machine to the storage of the SCMT.
Relocate the SCMT to the destination server room.
Manually create the destination virtual machine, mount the bare metal restore ISO file, and boot it. Configure the IP address to connect to the SCMT.
Stop the source machine application service, but not shut down the host.
Perform incremental backup of the source machine.
Restore the backup to the destination virtual machine.
The destination virtual machine performs compatibility processing and automatically installs the performance optimization tool(vmTools). The VM will be restarted after installing vmTool and will take over the business normally.

1.When migrating a source VM with dynamically allocated disks, If the data volume exceeds 16TB (exceeding the size limit of dynamically allocated disks), the allocation will automatically switch to thin provisioning.

2.Migrating data from a single disk on the source side to multiple disks on the target side is not supported.

3.Migrating data from multiple disks on the source side to a single disk on the target side is not supported.

4.Migration of external storage with mounted partitions is supported; migration of raw disks without file system partitions is not supported.

5.Migration of file storage mounted on the source VM is not supported.

6.Migration can only proceed after installing the agent on source VM and preparing the target VM. Hot standby migration does not support automatic startup of the VM on HCI, manual preparation of the target VM is required.

Migration Time

The initial synchronization only transfers the actual used data blocks within the virtual machine's disk, not the entire provisioned capacity. For instance, if a VM has a provisioned disk of 100 GB but only 50 GB is utilized, the initial sync will transfer approximately 50 GB of data. Subsequent replications are incremental, capturing only the data blocks that have changed since the last sync. Following the final incremental sync, a planned service cutover is required. This involves stopping the services on the source machine and redirecting operations to the target. For Backup Migration, the service interruption during this cutover window is typically around 30 minutes.

No.	Migration Phase	Tasks	Estimated Duration
1	Pre-Migration Setup	1.1 Deploy the SCMT (One-time setup, approximately 10 min) 1.2 Install Agent on all source machines (2 min/machine) 1.3 Create a full backup strategy for source machines (Duration depends on data volume) 1.4 Create Virtual Machines on the destination (1 min/machine)	Duration: Approximately 30 minutes Impact during Backup: • Agent CPU usage: < 3% • Agent Memory peak: < 260 MB
2	Data Replication & Sync	2.1 Transfer data from the completed source backup to the migration server via the agent. 2.2 Manually create the target VM on the destination, mount the bare metal recovery boot media, start it up, and configure the IP address for communication with the migration tool. 2.3 Automatically inject VMTools and perform compatibility processing during the backup restoration.	Duration: Total Data Volume / Migration Speed • Max Speed: 100 MB/s (1 GbE), 500 MB/s (10 GbE) Source Resource Utilization: • Agent CPU usage: < 3% • Agent Memory peak: < 260 MB • Recommended free memory on source: > 1 GB • Default source storage performance cap: 30% (Queue Depth: 4) - Adjustable • Default source network bandwidth cap: 300 Mbps - Adjustable Note: Services must be stopped during the final cutover stage.
3	Service Cutover	3.1 Stop application services on the source machine (without shutting it down) (~10 seconds) 3.2 Restore the backup to the target PE environment (Duration depends on data volume) 3.3 Activate the target VM to officially take over services	Duration: • Steps 3.1 & 3.3: ~30-40 seconds • Step 3.2: Depends on data volume Impact: Source services stopped

Resumable Transfer

• If the source-end network is interrupted for less than 15 minutes, the backup task remains unaffected. Once the migration server is back online and stable, incremental data will automatically resume syncing.

• If the source-end network is interrupted for more than 15 minutes, the task is suspended. After the source-end status recovers, incremental data will automatically resume syncing.

• If the VM is restarted or shut down during migration, there is no impact on source-end services. After the target VM status is restored, a full data retransmission will be re-initiated.

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Sangfor Cloud Platform (SCP)

Backup Migration