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Configuring SnapReplicate™

Having prepared the environment on both SoftNAS AWS instances, we can now set up high availability. The first step towards high availability in SoftNAS is to establish replication. SnapReplicate™ makes this as simple as completing a quick wizard.

To establish the secure SnapReplicate relationship between two SoftNAS nodes, simply follow the steps given below:

  1. Log into the source controller's (the first instance within which you created the CIFS enabled volume) SoftNAS StorageCenter™ administrator interface using a web browser.

  2. In the Left Navigation Pane, select the SnapReplicate™/SNAP HA™ option.


    The SnapReplicate/SNAP HA page will be displayed.

  3. Click the Add Replication button in the Replication Control Panel.


    The Add Replication wizard will be displayed. Read the instructions on the screen and then click the Next button.

  4. In the next step, enter the IP address or DNS name of the remote, target SoftNAS controller node in the Hostname or IP Address text entry box. Note that by specifying the replication target's IP address, you are specifying the network path the SnapReplicate™ traffic will take. 


    The source node must be able to connect via HTTPS to the target node (similar to how the browser user logs into StorageCenter using HTTPS). HTTPS is used to create the initial SnapReplicate configuration. Next, several SSH sessions are established to ensure two-way communications between the nodes is possible. This connection is established by providing the IP address.

  5. Next, provide the username (softnas) and the password (if default, this is the instance id) of the target instance. Type the password again to verify, then click Next.


    The IP address/DNS name and login credentials of the target node will be verified. If there is a problem, an error message will be displayed. Click the Previous button to make the necessary corrections and then click the Next button to continue. 

  6. Read the final instructions and then click the Finish button.
     
    The SnapReplicate™ relationship between the two SoftNAS controller nodes will be established. The corresponding SyncImage of the SnapReplicate™ will be displayed.



    After data from the volumes on the source node is mirrored to the target, once per minute SnapReplicate™ transfers keep the target node hot with data block changes from the source volumes.

    The tasks and an event log will be displayed in the Replication Control Panel section. This indicates that a SnapReplicate™ relationship is established and that replication should be taking place.

Configuring SNAP HA™

SnapReplicate™ establishes a replication relationship, one that can be manually triggered or scheduled, but is not automated. For true high availability in a failover situation, SNAP HA™ must be configured as well. 

  1. To configure SNAP HA™, complete the SNAP HA wizard, beginning by clicking Add SNAP HA™.



    Note:Configuration of SnapReplicate™ is a prerequisite to setup of SNAP HA™.  If SnapReplicate™ is not configured, the Add SNAP HA™ button will be grayed out.

    If you have not yet configured a notification email, the opportunity to provide one will be presented prior to continuing SNAP HA™. Provide an email address for support reports and logs to be sent to, and click OK.

  2. Click Add SNAP HA™ once more if this occurs. The Add High Availability wizard will begin.




  3. Here you will create and add an IP Address that is within the same CIDR block as the instances. In simplest terms, ensure that the IP address starts with the same numbers as the two instances, but which is not in use. To avoid conflicts, list the private IPs of your virtual machines within the subnet, a well as any virtual IPs used for other HA pairings.
    Note:The update all subnets option is an advanced option that can be useful if you do not have a large number of subnets. If hundreds of subnets are in use, it is recommended not to select this option.
    Note:The Virtual IP on same subnet option should only be checked if using VNET peering. This too is an advanced option, and not within the scope of this guide.


    Click Next once the virtual IP has been provided.
     
  4. Next, you can tune the behavior of your HA pairing.


    1. You can determine the max number of retries before your virtual machine fails over.
    2. You can determine the max time (in seconds) that storage can be unavailable before a failover is triggered.
    3. You can also set a default for max ioping request time, to ensure that a failover is triggered more quickly in event of failure.
    4. Finally, you can determine the behavior of the failed node during a failover. 
      1. Reboot - this is the default option, allowing for quicker recovery and re-establishment of high availability, as the failed node will reboot, and SNAP HA will be reactivated, with the original node set as secondary.
      2. Shutdown - The failed node will remain shut down. You will need to reboot the instance manually to re-establish high availability. 
      3. None (No action taken) - This option is only for debug or support use. The failed node will remain in its current state. 

  5. Click Next. 

  6. Click Finish on the Finish HA Setup screen.

  7. Your SNAP HA™ pairing is created.

     

To test, shut down one of the instances. The other will become primary after a few moments. Alternatively, select Actions, and Takeover to simulate a failover. Follow the instructions found in Recovering from a High Availability Failure to re-establish your highly available configuration.




 


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