Pure Storage FlashArray-Storage-Professional Exam - Topic 5 Question 4 Discussion

The ActiveCluster Mediator (whether it is the Pure1 Cloud Mediator or the On-Premises VM) is a lightweight tie-breaker that communicates continuously with the management interfaces of both FlashArrays. If it was previously online and suddenly reports as 'unreachable' from both arrays simultaneously, the issue is almost always caused by a network interruption or firewall rule change blocking the required communication ports between the arrays' management IP addresses and the Mediator VM.

If a network firewall is suddenly configured to drop or deny outbound TCP traffic (such as port 80/443 depending on the specific HTTP/HTTPS discovery and heartbeat configuration) from the FlashArrays to the ESXi-hosted Mediator, the arrays will fail to send their heartbeats, causing the mediator status to drop to 'unreachable.'

Here is why the other options are incorrect:

Fibre Channel (FC) zoning or network access has not been created properly for the host (A): The Mediator is completely independent of the front-end host storage fabric (Fibre Channel or iSCSI). Host zoning issues would prevent the ESXi server from seeing its volumes, but it would not cause the FlashArrays to lose management network connectivity to the Mediator.

The mediator does not reside within a Pure datastore (B): This is actually a strict best practice and requirement. Pure Storage explicitly states that the On-Premises Mediator VM must be deployed in a separate (third) failure domain. It should not reside on the ActiveCluster mirrored datastore, because a site-wide SAN failure would take the mediator offline exactly when it is needed most. Therefore, not residing on a Pure datastore is the correct setup, not a cause for an outage.