Itzikr's Blog

On June 10th, 2021, Dell Technologies released PowerStore OS version 2.0. This release brought many new features, enhancements, and capabilities to the fast growing PowerStore user base. One of those new features is a Disaster Recovery (DR) testing feature that is seamlessly integrated into PowerStore Manager (the HTML5 GUI).

In the image above you can see the addition of a new button that allows an administrator to initiate a “Failover Test” which allows for seamless DR testing. This feature exists on the target array which is the destination array for a replication agreement. So literally by the click-of-a-button a full DR test can performed.

Key Concepts of the DR Test Feature

1. It is a completely seamless and integrated capability of PowerStore’s native asynchronous replication
2. Simulates a fully featured failover to the Disaster Recovery site
3. During the test the DR location has full read-write access to the mapped volumes at the DR site
4. The testing period has no time restrictions meaning the testing period can be as long or as short as you want
5. Production data and replication session is NOT impacted by performing a DR Test. Your production replication and protection continues while the DR Failover Test is taking place.
6. The DR Failover Test can be performed with the most recently synchronized data or any available snapshot

Defining Source and Destination

As I mentioned, this is predicated on having a replication agreement setup with what we call a source array and a destination array.

The source array, as shown in the image above, is the production array that houses your production volumes. The destination or target is another PowerStore array that in a replication agreement and is the receiving target for your replicated production data. Note that the destination systems volumes are in a “Read-Only” state while they are actively part of an active replication agreement. This protects the destination from being overwritten and preserves the integrity of the data within the DR destination system.

The source and destination setup is extremely simple and can be implemented via an intuitive wizard and protection policies. In fact, adding a volume to an pre-defined protection policy at the point of creation will automagically establish the replication agreement and schedule for you.

Note in the image above, during the volume creation process, you can create a single volume or hundreds of volumes and have the replication schedules applied instantly via the Volume Protection Policy. The Volume Protection Policy allows you to customize snapshot and replication schedules based on your needs and then apply the policy instantly to a volume or volume group. There is no need to manage replication sessions for each and every volume… click… click… done! It is that simple.

Once the DR Failure Test is initiated (click the button) the destination array makes the target data read-writeable while isolating the production continuous replication stream (see below image).

Let’s Make it Happen

The steps to making a DR Failover Test happen are extremely simple, so let’s make it happen in 1…2…3…!

1. On the Destination array go to the volume properties and select the Protection tab. Once in Protection tab select the Replication tab to view the replication status. It is here you will see the START FAILOVER TEST button.

2. Press the START FAILOVER TEST button

3. Next you are prompted to use the most recently synchronized data OR you can choose to use any pre-existing snapshot.

Let’s use the most current data for this example… Select the START FAILOVER TEST button to confirm. Once this step is completed you are done! All that is left to do is mount the DR Test Volume to the DR hosts which will now have read-write access.

You can tell that you are in DR Test mode by the refreshed Replication properties screen (see below image):

Once you have completed your DR testing scenario and validated your test process and data you can STOP FAILOVER TEST from the same screen. A very nice feature to the STOP FAILOVER TEST process is the ability to preserve your testing data if desired. When you press the STOP FAILOVER TEST button you are immediately greeted with a confirmation with the ability to preserve your testing data. If you check the box, a snapshot will be automatically created preserving all of your testing data (new writes to the volume).

Clicking STOP FAILOVER TEST on this confirmation screen instantly stops the DR FAILOVER TEST and returns the destination volume back to its synchronized state with the original production volume.

Note in the image above the volume replication screen provides the following notification: The failover test has been stopped. The read/write mode has been disabled on the destination resource.

Summary

Simplicity is the key. PowerStore creates replication sessions for you automatically based on the protection policy you define for volumes or volume groups. Once a replication session has been initiated the DESTINATION system will have the DR FAILOVER TEST option available under the protection/replication properties tab. And that is DR Testing made simple!

More details about DR FAILOVER TEST can be found in the PowerStore Protecting Your Data guide.

You can also view a video based demo of the DR FAILOVER TEST option on the Dell EMC YouTube Channel.

A guest post by Jodey Hogeland