Setting Up Advanced Replication Tasks

Go to Data Protection > Replication Tasks and click ADD, then select ADVANCED REPLICATION CREATION.

• General Options:
  • Name the task.
  • Select Push or Pull for the local system.
  • Select a replication transport method.
    • SSH is recommended.
    • SSH+Netcat is used for secured networks.
    • Local is for in-system replication.
• Configure the replication transport method:
  • Remote options require a preconfigured SSH connection.
  • SSH+Netcat requires defining netcat ports and addresses.
• Sources:
  • Select sources for replication.
  • Choose a preconfigured periodic snapshot task as the source of snapshots to replicate.
  • Remote sources require defining a snapshot naming schema.
• Destination:
  • Remote destination requires an SSH connection.
  • Select a destination or type a path in the field.
  • Define how long to keep snapshots in the destination.
• Scheduling:
  • Run automatically starts the replication after a related periodic snapshot task completes.
  • To automate the task according to its own schedule, set the schedule option and define a schedule for the replication task.

The Transport selector determines the method to use for the replication: SSH is the standard option for sending or receiving data from a remote system, but SSH+NETCAT is available as a faster option for replications that take place within completely secure networks. Local is only used for replicating data to another location on the same system.

With SSH-based replications, configure the transport method by selecting the SSH Connection to the remote system that sends or receives snapshots. Options for compressing data, adding a bandwidth limit, or other data stream customizations are available. Stream Compression options are only available when using SSH. Before enabling Compressed WRITE Records, verify that the destination system also supports compressed WRITE records.

For SSH+NETCAT replications, you must define the addresses and ports to use for the Netcat connection.

Allow Blocks Larger than 128KB is a one-way toggle. Replication tasks using large block replication only continue to work as long as this option remains enabled.

The replication Source is the datasets or zvols to use for replication. Select the sources to use for this replication task by opening the file browser or entering dataset names in the field. Pulling snapshots from a remote source requires a valid SSH Connection before the file browser can show any directories.

If the file browser shows a connection error after selecting the correct SSH Connection, you might need to log in to the remote system and configure it to allow SSH connections.

In TrueNAS, do this by going to the System Settings > Services screen, checking the SSH service configuration, and starting the service.

By default, the replication task uses snapshots to quickly transfer data to the receiving system. When Full Filesystem Replication is set, the task completely replicates the chosen Source, including all dataset properties, snapshots, child datasets, and clones. When choosing this option, we recommended allocating additional time for the replication task to run.

Leaving Full Filesystem Replication unset but setting Include Dataset Properties includes just the dataset properties in the snapshots to be replicated.

Checking the Recursive check box allows you to recursively replicate child dataset snapshots or exclude specific child datasets or properties from the replication.

Enter newly defined properties in the Properties Override field to replace existing dataset properties with the newly defined properties in the replicated files.

List any existing dataset properties to remove from the replicated files in the Properties Exclude field.

Local sources are replicated by snapshots that were generated from a periodic snapshot task and/or from a defined naming schema that matches manually created snapshots.

Select a previously configured periodic snapshot task for this replication task in the Periodic Snapshot Tasks drop-down list. The replication task selected must have the same values in Recursive and Exclude Child Datasets as the chosen periodic snapshot task. Selecting a periodic snapshot schedule removes the Schedule field.

To define specific snapshots from the periodic task to use for the replication, set Replicate Specific Snapshots and enter a schedule. The only periodically generated snapshots included in the replication task are those that match your defined schedule.

Remote sources require entering a snapshot naming schema to identify the snapshots to replicate. A naming schema is a collection of strftime time and date strings and any identifiers that a user might have added to the snapshot name. For example, entering the naming schema custom-%Y-%m-%d_%H-%M finds and replicates snapshots like custom-2020-03-25_09-15. Multiple schemas can be entered by pressing Enter to separate each schema.

Alternately, you can use your Replication Schedule to determine which snapshots are replicated by setting Run Automatically, Only Replicate Snapshots Matching Schedule, and defining when the replication task runs.

When a replication task is having difficulty completing, it is a good idea to set Save Pending Snapshots. This prevents the source TrueNAS from automatically deleting any snapshots that failed to replicate to the destination system.

Use Destination to specify where replicated data is stored. Choosing a remote destination requires an *SSH Connection to that system. Expanding the file browser shows the current datasets that are available on the destination system. You can click a destination or manually type a path in the field. Adding a name to the end of the path creates a new dataset in that location.

DO NOT use zvols as remote destinations.

By default, the destination dataset is set to be read-only after the replication is complete. You can change the Destination Dataset Read-only Policy to only start replication when the destination is read-only (REQUIRE) or to disable checking the dataset’s read-only state (IGNORE).

The Encryption checkbox adds another layer of security to replicated data by encrypting the data before transfer and decrypting it on the destination system.

• Setting the checkbox adds more options to choose between using a HEX key or defining your own encryption PASSPHRASE.
• You can store the encryption key either in the TrueNAS system database or in a custom-defined location.

Synchronizing Destination Snapshots With Source destroys any snapshots in the destination that do not match the source snapshots. TrueNAS also does a full replication of the source snapshots as if the replication task had never been run before, which can lead to excessive bandwidth consumption.

This can be a very destructive option. Make sure that any snapshots deleted from the destination are obsolete or otherwise backed up in a different location.

Defining the Snapshot Retention Policy is generally recommended to prevent cluttering the system with obsolete snapshots. Choosing Same as Source keeps the snapshots on the destination system for the same amount of time as the defined Snapshot Lifetime from the source system periodic snapshot task.

You can use Custom to define your own lifetime for snapshots on the destination system.

By default, setting the task to Run Automatically starts the replication immediately after the related periodic snapshot task is complete.

Setting the Schedule checkbox allows scheduling the replication to run at a separate time.

• Defining a specific time for the replication task to run is a must-do.
• Choose a time frame that both gives the replication task enough time to finish and is during a time of day when network traffic for both source and destination systems is minimal.
• Use the custom scheduler (recommended) when you need to fine-tune an exact time or day for the replication.

Setting Only Replicate Snapshots Matching Schedule restricts the replication to only replicate those snapshots created at the same time as the replication schedule.