SC//HyperCore Replication

Systems running SC//HyperCore™ HyperVisor offer replication at the VM level, so you can easily manage VMs for disaster recovery. One-to-one replication covers both Source-to-Target replication and “cross replication,” where the Target also replicates back to the Source system.

Replication is a near-continuous process that uses VM snapshots to send changes. If some changes are not yet sent when a new snapshot is due, replication finishes sending them before it moves on to the next scheduled snapshot.

To use custom schedules, see Snapshot Schedules for a Virtual Machine.

Replication uses network compression by default. You can exclude virtual hard disks on a VM from replication, but only by engaging Scale Computing Support. This is useful for transient or temporary data such as Windows pagefiles, SQL temporary databases, log data, print queues, etc.

Prerequisites

Before you enable replication, make sure you have the following in place:

  • Local (Source) and remote (Target) SC//HyperCore systems accessible to each other over the LAN network.
  • The LAN IP for one of the nodes in the Target system.
  • The SC//HyperCore web interface login credentials for the Target system.
  • Port 10022 opened between the Source and Target systems (the default replication port).

Replication works only between compatible SC//HyperCore versions. A warning appears when you set up a Remote Connection to an incompatible system, and any replication attempt fails with a logged error. See SC//HyperCore Replication Version Compatibility for supported version pairs.

Add, Monitor, or Remove a Remote System Connection

Set up a Remote System Connection with the Target system before you start replication on the Source system VMs. Always pause all replication connections before a physical system move or other networking topology change.

Before you remove the Target system’s Remote System Connection, pause replication on every replicating VM on the Source system (or remove the VMs from replication completely). Any VM still replicating when the connection is deleted will stop taking snapshots entirely, local snapshots included, until a snapshot schedule is reassigned. See Cancel Virtual Machine Replication and Snapshot Schedules for a Virtual Machine.

Add:

  1. Open the Control Center or the Snapshots and Replication screen on the Source system.
  2. Click the Remote Systems tab or click Setup Replication in the Snapshots and Replication screen.
  3. Click + Add System.
  4. Enter the LAN IP of a node from the Target system in the Node field.
  5. Enter the Username and Password used to access the SC//HyperCore web interface on the Target system.
  6. Click Create to save the settings and start the replication connection.

Monitor:

  • Once added, the remote SC//HyperCore HUD appears in the list of Remote Clusters. Values can take up to an hour to fill in after the first connection.
  • Click a remote system’s HUD to open its SC//HyperCore web interface in a new browser tab.

Remove:

  1. For each VM that is being replicated, follow the steps in Cancel Virtual Machine Replication.
  2. Open the Control Center on the Source system.
  3. Click the Remote Systems tab.
  4. Click the orange X in the upper right corner of the remote system you want to remove.
  5. Click Delete Connection to confirm.

Replicate a Virtual Machine

If you replicate a VM that has a vTPM attached, the Boot Type you chose at VM creation affects DR recoverability. Replicating a vTPM + security-enabled VM to a cluster with any node older than SkyLake CPU generation requires the UEFI + vTPM (Compatibility) Boot Type, or the vTPM may deny access to the guest OS on failover. See vTPM Support in SC//HyperCore.

  1. Open the Snapshots and Replication screen on the VM card.
  2. Click Setup Replication next to the Replication icon. A popup dialog appears.
  3. Select the connected remote system from the Target dropdown list.
  4. Click Replicate to confirm and start the VM replication.

Once started, replication uses the snapshot feature to estimate the rate of change and send new data to the Target system. Replication is a near-continuous process. You can monitor its state (idle, active, or paused) on the Snapshots and Replication screen on the VM card.

When replication is configured and the first job is complete, a VM replication card appears on the Target system. It holds the replicated images of the Source VM, stored in snapshot copies.

Pause or Resume Replication of a Virtual Machine

Pausing a VM during replication halts replication and stops all automated snapshots. Resuming picks up where the job was halted and restarts automated snapshots.

  1. Open the Snapshots and Replication screen on the VM card on the Source system.

Pause: Click the Pause Replication icon.

Resume: Click the Resume Replication icon.

Restore from a Replicated Virtual Machine

When you run a Disaster Recovery (DR) test, prevent IP conflicts with the primary VM. Either disconnect the NIC(s) of the VM restored from the replication VM card, or isolate the restored VM’s traffic with a VLAN.

  1. Open the SC//HyperCore web interface for the Target system.
  2. Find the replicated VM card you want to restore from.
  3. Choose the snapshot to restore from:
    • To restore from the latest snapshot, click the Clone VM icon on the VM card.
    • To choose another snapshot, click the VM Replication icon to see all available snapshots. Then click Clone VM next to the snapshot you want.

A new VM is cloned from the snapshot image.

Cancel Virtual Machine Replication

To stop replicating a single VM, pause replication on the Source system and delete the replicated VM on the Target system.

  1. Open the Snapshots and Replication screen on the VM card on the Source system.
  2. Click the Pause Replication icon. Replication pauses.
  3. Open the SC//HyperCore web interface of the Target system.
  4. Click the Delete VM icon on the replicated VM card for the VM you want to remove from replication.

The VM stops replicating to the Target system as long as replication is paused.

To remove a VM from replication permanently, clone the Source system VM and delete the original VM in the replication job. Then power on the clone VM as the primary VM from then on. This needs a short window of downtime to switch to the cloned VM.