# Remote Clones

## Remote cloning introduction

The Remote Clone feature makes a specified snapshot of a source volume
instantly available as a volume on another VPSA.
The snapshot is available before data is copied, in the same cloud or in a
different cloud, and over any distance.
The cloned new volume is immediately available, in contrast to mirroring
that might take a long time to replicate data, which depends on capacity and
link bandwidth.

<a id="remote-cloning-modes"></a>

## Remote cloning modes

The remote cloning process can run in one of two modes:

<a id="remote-cloning-on-demand-mode"></a>

### On-demand mode

The cloned volume retrieves blocks of data from the source volume on
demand, as needed.
During that time, the clone behaves like any other volume, but is
dependent on its source volume.
After all the data is copied to the clone, the relation between the
source and cloned volumes breaks, and the cloned volume becomes a
regular volume.

<a id="remote-cloning-background-mode"></a>

### Background mode

The system retrieves all the data from the source volume in the
background.
In this mode, after all the data is retrieved, the connection to the
original snapshot breaks and the volume becomes independent.

<a id="remote-cloning-use-cases"></a>

## Common remote cloning use cases

The most common remote cloning use cases are:

<a id="remote-cloning-instant-mobility"></a>

### Instant mobility

Instant mobility is the rapid migration of volumes between VPSAs with
minimal downtime for the application accessing the migrating volume.

Instant mobility is useful for:

- Volume migration from a VPSA that runs out of capacity, into a VPSA
  that has free capacity
- Volume migration between VPSA Storage Array
  and VPSA Flash Array
- Volume migration between sites
- Volume migration from a private cloud to the public cloud

<a id="remote-cloning-offline-processing"></a>

### Offline processing

Offline processing requires the creation of an instant clone of a volume on
another VPSA (local or remote). The new cloned volume can then be used for
offline processing, without affecting the original production volume.

Offline processing is useful for:

- Development and Test
- Analytics
- Reporting

The following table summarizes an example of a sequence of steps, including
high-level steps for remote cloning, for implementing the
[Instant mobility](#remote-cloning-instant-mobility) or
[Offline processing](#remote-cloning-offline-processing) use cases:

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| Step         | Action                                                                                                                                                                                        | For instant<br/>mobility   | For offline<br/>processing   |
|--------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------|------------------------------|
| 1            | If relevant:<br/><br/>Stop the application that accesses the volume to be migrated.                                                                                                           | ✓                          | ✗                            |
| 2            | Take a snapshot of the volume to be cloned from the source VPSA.<br/><br/>See [Manual creation and deletion of snapshots](snapshots-and-snapshot-policies.md#creation-deletion-of-snapshots). | ✓                          | ✓                            |
| 3            | [Connect source and destination VPSAs](#connect-source-destination-vpsas).                                                                                                                    | ✓                          | ✓                            |
| 4            | [Create a remote clone](#create-remote-clone).                                                                                                                                                | ✓                          | ✓                            |
| 5            | [Attach a clone to a server](#attach-clone).                                                                                                                                                  | ✓                          | ✓                            |
| 6            | If relevant:<br/><br/>Start offline processing on the server accessing the new volume.                                                                                                        | ✗                          | ✓                            |
| 6<br/><br/>7 | If relevant:<br/><br/>Restart the application that will access the new volume.                                                                                                                | ✓                          | ✗                            |
<br/>

<a id="connect-source-destination-vpsas"></a>

## Connect source and destination VPSAs

A clone can only be created on a pair of VPSA’s that are known to each other.
To establish the connection between VPSAs, remote VPSAs are discovered and
defined in the same way as for remote mirroring.

If the VPSAs are located in different Zadara Storage Clouds, you will
need to first assign a public IP to each VPSA.

Follow the details in [Connect to a remote VPSA](remote-vpsa.md#connect-to-a-remote-vpsa) to discover the
remote VPSA and establish a connection.

<br/>

<a id="create-remote-clone"></a>

## Create a remote clone

A remote cloned volume is created on the destination VPSA as a new type
of volume.

To create a remote cloned volume:

1. Go to  **Resources > Volumes**.
2. In the **Volumes** view, click **Create** and select
   **Create Volume from Remote Snapshot** from the dropdown.

   ![imageSelectRemoteClone](media/SelectRemoteClone.png)
3. In the **Create Volume from Remote Snapshot** dialog that opens,
   select the source VPSA volume’s snapshot to clone:

   ![imageCreateRemoteClone1](media/CreateRemoteClone1.png)
   1. **Source VPSA**: From the list of VPSAs in the dropdown, select the
      remote VPSA from which to clone.
   2. **Source Volume**: From the list of volumes in the dropdown, select
      the remote VPSA’s volume to clone. The selected volume’s list of
      snapshots is displayed in the **Source Snaphot** table.
   3. **Source Snapshot**: Click the snapshot to use, from the list of
      snaps of the selected source volume.
   4. Click **Next**. The dialog switches, for entering the destination
      volume details.

      ![imageCreateRemoteClone2](media/CreateRemoteClone2.png)
   5. **NewVolume Name**: Enter a name for the new volume.
   6. **Select a Pool**: From the list of available storage pools, click
      the pool from which to allocate storage resources for the new volume.
   7. **Encrypted**: To encrypt the new volume, mark the checkbox.
   8. VPSA Flash Array To dedupe or compress a new volume on a VPSA Flash Array,
      mark the checkboxes.
   9. Select the **Retrieval Mode** for the cloning process:
      * **On-Demand**: Blocks of data are retrieved as needed, until
        all the source volume data is copied to the destination volume.
      * **Background**:  All the source volume’s data is retrieved in
        the background.
   10. Click **Create**.

<br/>

## Monitoring a remote clone

### Destination VPSA

![imageMonitorRemoteClone](media/MonitorRemoteClone.png)

- Cloned volume properties are identical to those of a regular volume.
- Capacity of a clone shows the virtual capacity of the original volume,
  and the physical capacity of the cloned volume.
- While retrieving data, the system detects whether the clone is connected.
  If connectivity to the source snapshot is lost during data retrieval, the
  clone becomes unavailable.
- During the cloning process, the destination volume is listed in the
  **Volumes** table with its **Status** column entry displaying the value
  `Cloning` together with a connectivity icon, indicating the activity
  in progress.
- The cloning data retrieval’s status is displayed on the south
  panel’s **Remote Snapshot Status** tab, while data is copied from the
  source volume to its clone.
- During the cloning process, you can break the connection between the
  clone and its origin, by clicking the **Break** button in the
  **Remote Snapshot Status** tab.
- During the cloning process in **Background** mode, there are also controls
  to **Pause** and **Resume** the data transfer. This feature is useful
  when experiencing load problems on the system.
- After all the data is retrieved, the relationship between the source and
  the cloned volumes is broken, the cloned volume becomes a regular
  volume and the **Remote Snapshot Status** tab is no longer displayed.

### Source VPSA

![source-vpsa-remote-clones-tab](media/source-vpsa-remote-clones-tab.png)

- On the source VPSA during the cloning process, the south pane of a source
  volume being cloned displays the additional **Remote Clones** tab.
  This tab lists the names and details of the destination volumes in the
  process of being cloned from the selected source, and the destination
  VPSA on which they are being cloned.
- On completion of a cloning process, the entry of the successfully cloned
  remote volume disappears from the table in the source volume’s
  **Remote Clones** tab.
  On completion of all cloning processes for a source volume, there are no
  longer any entries in the table in its **Remote Clones** tab, and the
  tab is no longer displayed.

<br/>

<a id="attach-clone"></a>

## Attach a clone to a server

A remote clone is attached to servers on the target VPSA, in the same way
as a regular volume.
Similarly, a cloned volume can be detached from a server in the same way as
a regular volume.
Follow the instructions in [Attaching & detaching Volumes to Servers](volumes.md#attaching-detaching-volumes-to-servers).

<br/>

## Data services

The following data services are not available on destination volumes while
the source data is being retrieved:

- Snapshots
- Clones
- Mirrors
- B2OS

After all the data is retrieved and the relationship between the source and
the clone has been broken, all data services become available.

<br/>

## Delete a clone

Deletion of a remote cloned volume is done on the destination VPSA, and it
breaks the relations with the source volume.
You can delete a remote clone in the same way that you delete any other volume.
Follow the instructions in [Creating and Deleting a Volume](volumes.md#creating-and-deleting-a-volume).