Distributed virtual volumes are a key component of Dell VPLEX that enable active-active data center configurations. Here’s how they contribute to this capability:

Active-Active Data Centers: In an active-active data center setup, both data centers are actively running workloads and can take over for each other in case of a failure.This configuration requires a storage solution that can provide simultaneous access to the same data from multiple locations1.

Distributed Virtual Volumes: VPLEX creates distributed virtual volumes that span across two geographically separated clusters.These volumes can be accessed and written to simultaneously from both locations, which is essential for maintaining operations in an active-active environment1.

Cache Coherence: VPLEX uses a cache coherence algorithm to ensure that write operations are synchronized across both sites.This means that when data is written to a distributed virtual volume, it is updated in both locations at the same time, ensuring consistency1.

Application Support: Distributed virtual volumes support mission-critical applications that require high availability and continuous operations, such as Oracle RAC, by allowing them to operate in an active-active manner across data centers1.

VPLEX Metro: The VPLEX Metro product supports active-active data centers by allowing applications to simultaneously read and write on both sites, which increases resource utilization and provides infrastructure that is actively used rather than remaining idle2.

By leveraging distributed virtual volumes, VPLEX enables organizations to create highly available, geographically distributed virtual data centers that support continuous data access and mobility.

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 ones1.

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 it1.

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 arrays1.

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 arrays1.

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 protection1.

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.

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 operations1.

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 integrity1.

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 scenario1.

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.

Before a host can detect the virtual volumes presented by VPLEX, it is necessary for the host to initiate a bus-scan of the Host Bus Adapters (HBAs). This process allows the host to recognize new storage devices that have been presented to it, such as the virtual volumes from VPLEX.

Here’s a detailed explanation:

Host Bus Adapters (HBAs): HBAs are the hardware interfaces that connect a host system to a network or storage device. In the context of VPLEX, they connect the host to the VPLEX storage system.

Bus-Scan: A bus-scan is a command that can be issued from the host to scan the storage network for any changes, such as newly added storage volumes. This is typically done using operating system-specific commands or utilities.

Virtual Volumes Detection: Once the bus-scan is complete, the host’s operating system can detect the virtual volumes presented by VPLEX and make them available for use by applications and services running on the host.

No RAID Requirement: The detection of virtual volumes does not require RAID configuration to be enabled for the volumes themselves, as this is managed within the VPLEX system.

No Reboot Necessary: It is not necessary to reboot the host to detect virtual volumes. A bus-scan can be performed while the system is running without requiring a restart.

No Wizard Required: The EZ Provisioning wizard is a tool used within the VPLEX system for provisioning storage, but it is not required to be run on the host for virtual volume detection.

By initiating a bus-scan of the HBAs, the host can detect and utilize the virtual volumes presented by VPLEX, allowing for flexible and dynamic storage management.

When a director fails and is removed from a VPLEX cluster, the global cache size decreases. This is because each director contributes to the total global cache available in the VPLEX cluster. Here’s the explanation:

Global Cache: The global cache in a VPLEX system is a shared resource that is used by all directors in the cluster to cache data for improved performance1.

Director Contribution: Each director within the VPLEX cluster has its own local cache, which collectively forms the global cache.When a director is operational, its cache is part of the global cache pool1.

Director Failure: If a director fails, its cache is no longer available to the cluster.As a result, the total size of the global cache is reduced by the amount that was contributed by the failed director1.

Removal from Cluster: When the failed director is physically removed from the cluster, its cache is permanently removed from the global cache pool, resulting in a decrease in the total global cache size1.

Impact on Performance: The reduction in global cache size may impact the performance of the VPLEX system, as there is less cache available for data storage and retrieval operations1.

System Architecture: VPLEX architecture allows for multiple director failures without loss of access to data down to a single director, but the global cache size will decrease with each director failure1.

By understanding the role of each director’s cache in contributing to the global cache, administrators can anticipate the effects of director failures on the overall performance of the VPLEX system.

To add a RecoverPoint cluster to VPLEX, the RecoverPoint cluster Management IP address is required. This IP address is used to establish communication between the VPLEX system and the RecoverPoint cluster for management and replication purposes.

RecoverPoint Cluster Management IP Address: The management IP address is a unique identifier that allows the VPLEX system to connect to the RecoverPoint cluster.It is used for configuration, management, and monitoring of the RecoverPoint system from VPLEX1.

Adding a RecoverPoint Cluster: To add a RecoverPoint cluster to VPLEX, the administrator must use the VPLEX CLI and provide the management IP address of the RecoverPoint cluster.This is done using the rp rpa-cluster add command followed by the -o option to specify the IP address1.

Authentication: After providing the IP address, the administrator will be prompted to enter the administrative password for the RecoverPoint cluster to authenticate the connection1.

Verification: Once the RecoverPoint cluster is added, the administrator can verify the addition by using the ls recoverpoint/rpa-clusters/ command to list the RecoverPoint clusters connected to VPLEX1.

Management and Replication: With the RecoverPoint cluster added to VPLEX, the system can manage replication tasks and ensure data protection across the connected storage systems1.

By providing the RecoverPoint cluster Management IP address, administrators can integrate RecoverPoint with VPLEX, enhancing the system’s capabilities for data replication and disaster recovery.