In a VPLEX Metro cluster without a VPLEX Witness and with a static rule set to “cluster-2 detaches”, the result of a WAN COM failure would be as follows:

Delay Timer : Initially, VPLEX starts a delay timer upon detecting the WAN COM failure. This timer allows for a temporary network issue to be resolved without immediate impact on I/O operations 1 .

Suspension of I/O : While the delay timer is active, VPLEX suspends I/O to all distributed devices on both clusters to prevent data corruption and ensure data integrity 1 .

Resumption of I/O : If the WAN COM connectivity is not restored within the expiration period of the delay timer, VPLEX will resume I/O operations on Cluster-2, as per the static rule set. I/O will remain suspended on Cluster-1 to maintain a consistent data state and prevent a split-brain scenario 1 .

This process ensures that data remains consistent and available on at least one cluster in the event of a WAN COM failure, aligning with the predefined static rule set and maintaining the integrity of the VPLEX Metro cluster operations.

When considering the use of a VPLEX logging volume, it is important to note that a logging volume must be created on each VPLEX cluster before creating a distributed device. This is because logging volumes play a critical role in the VPLEX architecture by capturing write logs that are essential for data consistency and recovery processes.

Role of Logging Volumes : Logging volumes in VPLEX are used to store write logs that ensure data consistency across clusters, especially in distributed device configurations 1 .

Creation Before Distributed Devices : Before a distributed device can be created, which spans across clusters for high availability, logging volumes must exist on each cluster to handle the write logging required for the distributed device 1 .

VIAS and Automatic Provisioning : While VIAS (VPLEX Integrated Array Services) is a tool that simplifies storage provisioning tasks, and automatic provisioning can occur in certain scenarios, the creation of logging volumes is a prerequisite step that typically requires explicit action by the administrator before distributed devices are set up 1 .

Sequence of Operations : The sequence of operations is such that logging volumes are created first, providing the necessary infrastructure for capturing write logs, followed by the creation of distributed devices that will utilize these logging volumes 1 .

By ensuring that logging volumes are created on each VPLEX cluster prior to the creation of distributed devices, administrators can maintain the integrity and high availability of data within the VPLEX environment.

When using VPLEX with RecoverPoint enabled consistency groups, it’s important to consider how journals are managed:

Production Journals : These are used by the production volumes for logging write I/Os before they are replicated to the remote site or local copy.

Local Copy Journals : These are used by the local copy volumes for the same purpose as production journals but are specific to the local copies.

Separation of Journals : To ensure proper replication and recovery processes, production and local copy journals must be kept in separate consistency groups. This separation is crucial for maintaining the integrity of the replication and avoiding conflicts between production and local copy operations 1 .

RecoverPoint Configuration : In a VPLEX environment, RecoverPoint provides continuous data protection and replication. It is configured to work with VPLEX consistency groups to ensure that all writes are captured and can be recovered in case of a failure 1 .

Best Practices : Dell’s best practices for VPLEX RecoverPoint configurations recommend this separation of journals to ensure that the system can handle failover scenarios correctly and that data is not lost or corrupted 1 .

By following this consideration, storage administrators can ensure that their VPLEX RecoverPoint environment is configured for optimal data protection and disaster recovery readiness.

A supported geometry for a VPLEX device is RAID-C, which stands for RAID Concatenation. RAID-C is a VPLEX-specific RAID configuration that concatenates multiple extents or devices to create a larger virtual volume.

RAID Concatenation (RAID-C) : RAID-C is a VPLEX geometry that allows for the concatenation of multiple storage extents or devices. This configuration is used to create larger virtual volumes by combining smaller ones 1 .

Use of RAID-C : RAID-C is typically used when there is a need to expand storage capacity without the requirement for additional redundancy. It is a simple way to increase the size of a virtual volume by adding more storage to it 1 .

Advantages : The advantage of using RAID-C is that it allows for flexibility in storage provisioning and can be easily expanded as storage needs grow. It also enables the use of storage from different arrays 1 .

VPLEX Device Configuration : In the context of VPLEX, a device refers to a logical unit that can be presented to hosts. By using RAID-C geometry, VPLEX can present larger logical units that span across multiple physical storage arrays 1 .

Supported Geometries : VPLEX supports various RAID geometries, including RAID-0, RAID-1, and RAID-C, each serving different purposes and providing different levels of performance and protection 1 .

By utilizing RAID-C geometry, VPLEX administrators can manage storage more effectively, ensuring that they can meet the capacity requirements of their applications and services.

When setting up a VPLEX system that uses ESRS (EMC Secure Remote Services), it is essential to ensure that the correct ports are open to allow for various types of communication, including access to the VPLEX GUI. The port that needs to be opened on the firewall to allow access to the VPLEX GUI is port 443.

Port 443 : This port is commonly used for HTTPS traffic, which is the protocol used for secure web communications. The VPLEX GUI is accessed over a web browser using HTTPS, hence the need for port 443 to be open 1 .

Firewall Configuration : The firewall administrator must configure the firewall to allow inbound and outbound traffic on port 443 to the VPLEX system’s IP address. This ensures that the technical support engineer and other users can access the VPLEX GUI through a secure connection 1 .

Troubleshooting Access Issues : If the technical support engineer cannot access the VPLEX GUI, one of the first steps in troubleshooting is to check the firewall settings to confirm that the necessary ports, including port 443, are open 1 .

ESRS Communication : While ports 25, 9010, and 5901 are important for ESRS communication and other services, they do not facilitate access to the VPLEX GUI. Port 25 is typically used for SMTP email services, port 9010 may be used for internal services, and port 5901 could be used for VNC or other remote access protocols 1 .

Secure Access : Opening port 443 not only allows access to the VPLEX GUI but also ensures that the communication is encrypted and secure, protecting sensitive data and system configurations 1 .

By opening port 443 on the firewall, the company ensures secure and reliable access to the VPLEX GUI for administration, monitoring, and troubleshooting purposes.

In a VPLEX Metro environment, the write rate on distributed volumes has a direct impact on VPLEX performance with respect to WAN bandwidth. Here’s how:

Distributed Volumes : Distributed volumes in VPLEX Metro span across two geographically separated clusters and are designed to provide continuous availability and data mobility 1 .

Write Operations : Write operations on distributed volumes require data to be written to both clusters before an acknowledgment is sent back to the host. This ensures data consistency across both sites 2 .

WAN Bandwidth : The Wide Area Network (WAN) bandwidth between the two clusters is a critical factor in the performance of these write operations. If the WAN bandwidth is insufficient, it can lead to increased latency and reduced throughput 3 .

Performance Impact : With only half the available WAN-COM paths, VPLEX can exceed bandwidth limitations on the existing WAN-COM paths, causing severe latency impacting the remote writes of distributed devices 3 .

Best Practices : VPLEX best practices indicate that the round-trip time (RTT) between VPLEX clusters shouldn’t exceed 5 ms to provide the best performance, and an RTT of 1 ms is recommended for a campus-wide network 2 .

By managing the write rate on distributed volumes and ensuring adequate WAN bandwidth, VPLEX Metro can maintain high performance and meet the required service levels for data availability and accessibility.

In a VPLEX Metro environment without a Cluster Witness, the detach rules set for consistency groups (CGs) dictate the behavior during a WAN COM failure. Here’s what happens:

WAN COM Failure : A WAN COM failure means that the communication link between the two clusters in a VPLEX Metro has been lost.

Detach Rules : Detach rules are predefined actions that determine which cluster will continue to service I/O for a distributed virtual volume in the event of a communication failure.

CG1 and CG2 : For App1, CG1 has a detach rule set with cluster-1 as the winner, meaning if there’s a WAN COM failure, cluster-1 will continue to service I/O for CG1, and I/O will be suspended at cluster-2. Conversely, for App2, CG2 has a detach rule set with cluster-2 as the winner, so cluster-2 will continue to service I/O for CG2, and I/O will be suspended at cluster-1.

Consequence of Extended WAN COM Failure : If the WAN COM failure is extended, the detach rules will be invoked, and each cluster will service the I/O for its respective application based on the set rules. This means that CG1 will be active on cluster-1 and suspended on cluster-2, and CG2 will be active on cluster-2 and suspended on cluster-1.

No Cluster Witness : Without a Cluster Witness, which usually arbitrates which cluster should remain active in case of a split-brain scenario, the detach rules are critical for maintaining data integrity and availability.

By setting appropriate detach rules, the company ensures that each application remains operational on one of the clusters, even during an extended WAN COM failure, thus maintaining availability according to the predetermined failover strategy.