Free D-VPX-OE-A-24 sample questions

Correct answer: detach-rule-local-com-critical

The `detach-rule-local-com-critical` rule set is designed for scenarios where local I/O availability is prioritized over remote data consistency in the event of an inter-cluster link failure. This rule allows the local cluster to detach and continue serving I/O from its local leg, ensuring application uptime at that site. The other options either pre-determine a winner or require manual intervention, which doesn't meet the requirement.

Correct answer: The host continues to read and write to the original back-end LUN, while VPLEX tracks new writes.

In-band encapsulation is designed to be non-disruptive. When initiated, VPLEX places itself in the data path. The host's I/O is directed to the VPLEX virtual volume, but VPLEX initially passes reads and writes through to the original LUN. Simultaneously, it uses a logging map to track new writes and begins a background copy of the data to a new target LUN. This ensures the host maintains continuous access to its data throughout the migration process.

Correct answer: It mirrors all incoming writes to both the source and target devices.

During a device mobility job, VPLEX maintains data consistency by creating a RAID-1 mirror between the source and target devices. All new writes from the host are synchronously written to both devices. This ensures that the target is an exact, up-to-date copy of the source when the background synchronization of existing data is complete, allowing for a seamless cutover.

Correct answer: True

This is true. A key architectural requirement of a MetroPoint topology is the use of three sites. Site A and Site B host the active-active VPLEX Metro cluster, and Site C hosts the RecoverPoint cluster and the journal volumes. This ensures that the journal, which contains the history of writes, is isolated from a disaster affecting either of the primary production sites, enabling robust point-in-time recovery.

Correct answer: To act as a tie-breaker during an inter-cluster link failure to prevent a split-brain scenario.

The cluster witness is a lightweight component located at a third site that is reachable by both VPLEX clusters. Its sole purpose is to provide a quorum device. If the link between the two clusters fails, each cluster will race to communicate with the witness. The cluster that successfully communicates with the witness is designated the 'winner' and continues I/O operations, while the other cluster suspends I/O. This prevents a 'split-brain' condition where both clusters might try to write to their respective copies of the data, leading to data corruption.

Correct answer: VS6 utilizes a full-mesh back-end fabric and more powerful CPUs, significantly increasing I/O throughput and scalability over VS2.

The primary architectural evolution from VS2 to VS6 is the move to newer hardware with more powerful multi-core CPUs and a faster, full-mesh back-end fabric (PCIe Gen3). This contrasts with the VS2's point-to-point back-end interconnect. The result is a substantial increase in performance, scalability, and I/O handling capacity, which is a common driver for upgrading.

Correct answer: device attach-mirror

When a leg of a RAID-1 device fails or is taken offline, it must be manually re-attached to initiate the rebuild process. The `device attach-mirror` command is used to specify the mirror (the dead leg) that needs to be brought back into the RAID-1 set. Once attached, VPLEX will automatically begin synchronizing the data from the healthy leg to the re-attached leg.

Correct answer: The write is acknowledged after it has been committed to the caches of both the local and remote VPLEX clusters.

VPLEX Metro maintains cache coherency across sites. For a write I/O to be acknowledged, the data must be written to the local director's cache, transmitted across the WAN link, and successfully written to the remote director's cache. This ensures that both sites have a consistent, cached copy of the latest data before the host is notified of completion. The actual write to the back-end arrays (destaging) happens later as a background process.

Correct answer: A RAID-C device

RAID-C stands for concatenated device. It is specifically designed to allow for the non-disruptive expansion of a virtual volume by adding new extents to the end of the device. This is ideal for file systems that cannot be resized online, as the expansion happens at the block level beneath the file system. While other RAID types can be expanded, RAID-C is the simplest and most direct method for this specific use case.

Correct answer: The host operating system needs to rescan the SCSI bus to detect the new LUN size.

Expanding a LUN at the storage level (in this case, VPLEX) does not automatically notify the host operating system of the size change. The host OS has already discovered the LUN with its original size. To recognize the new capacity, the host's SCSI bus must be rescanned. This action prompts the OS to re-query the LUN's attributes, including its size, making the new space available for use.