Remote Replication Concepts, Fail Over/Role Reversal

Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide

There are some key, critical design issues regarding remote replication that need to be addressed before designing a DR solution using remote replication.

•Distances involved (primarily the distance between the primary and secondary sites)

•The amount of data required to be replicated

•The recovery objectives should a disaster occur

•The requirements for database applications

For more details about designing a RR solution, please refer to the Dell PowerVault MD3600f/MD3620f

Remote Replication Design Guide.

Remote Replication Concepts

This section introduces you to primary, secondary, and replication repository, and describes how they interact to replicate data between arrays using the Remote Replication feature.

Primary and Secondary Virtual Disks

When you start remote replication, a replicated virtual disk pair is created and consists of a primary (local) virtual disk on the primary storage array and its replicated pair virtual disk on the secondary storage array.

Primary (Local) Virtual Disk

The primary virtual disk is the virtual disk that accepts host I/O and stores application data. When the replication relationship is first created, data from the primary virtual disk is copied in its entirety to the secondary virtual disk. This process is known as a full synchronization and is controlled by the local MD36X0f storage array and owner of the primary virtual disk. During a full synchronization, the primary virtual disk remains fully accessible for all normal read and write I/O operations. The local MD36X0f storage array is responsible for initiating remote writes to the secondary virtual disk to keep the data on the two virtual disks synchronized.

Secondary (Remote) Virtual Disk

The remote or secondary MD36X0f storage array receives remote writes from the primary MD36X0f storage array and applies these writes to the remote virtual disks. While these secondary virtual disks(replicas) are also regular virtual disks they are not directly accessible for I/O by any hosts: the remote storage array will not accept direct host write requests for those virtual disks acting as remote pairs. This is to prevent unintentional corruption of the data being replicated to these secondary virtual disks. Virtual disks in secondary mode can be mapped to hosts, and are seen as read only disks until later promoted to a primary mode (a role reversal). MD36X0f storage also provides a feature that allows secondary virtual disks to be read through the use of the Snapshot function.

NOTE: Only standard virtual disks may be used in any replicated virtual disk pair (no Snapshot virtual disks). There can be up to 16 defined virtual disk replication pairs per MD3600f storage array.

Fail Over/Role Reversal

During normal RR operations, the remote virtual disks are in target mode and not in primary virtual disk mode. This prevents host access of these virtual disks for normal I/O. In the event of a disaster or a catastrophic failure of the primary site, a role reversal can be performed to promote the secondary

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MD3620F, MD3600f specifications

Dell's MD3620F and MD3600F storage arrays are designed for businesses seeking dependable, high-performance storage solutions tailored to meet the demands of modern data management. These models offer a blend of scalability, efficiency, and advanced features, making them well-suited for a range of applications, from virtual environments to critical database operations.

One of the primary features of the MD3620F and MD3600F is their support for a hybrid storage architecture. This approach allows organizations to combine flash storage with traditional hard disk drives (HDDs) to optimize performance and cost. The MD3620F focuses heavily on all-flash configurations, delivering exceptional speed and lower latency, ideal for I/O-intensive workloads.

Scalability is another hallmark of these storage solutions. The MD3600F allows users to scale up to 120 drives, providing robust capacity to meet growing data needs. The MD3620F is engineered for environments where data availability and speed are paramount, with support for high IOPS (Input/Output Operations Per Second) and consistent performance under stress.

In terms of data management, both systems integrate with Dell’s proprietary software, which enhances operational efficiency through features like automated tiering. This technology optimizes data placement between different storage types based on access frequency, ensuring that hot data is readily available while reducing costs associated with less critical data.

Reliability is crucial for businesses that depend on their storage systems. The MD3620F and MD3600F come equipped with advanced data protection mechanisms, such as RAID support, which safeguards against data loss, and snapshot capabilities that provide point-in-time copies of data. Moreover, these solutions include hot-swappable components, ensuring minimal downtime for maintenance and repairs.

Connectivity is also a strong suit of these storage arrays. They support multiple connectivity options, including SAS and iSCSI, allowing for flexible integration into existing IT infrastructures. This adaptability enhances their appeal to a wide range of enterprise environments.

In summary, the Dell MD3620F and MD3600F stand out as robust storage solutions with a combination of hybrid and all-flash configurations, scalability, advanced data management tools, and enhanced reliability features. These characteristics make them ideal for organizations looking to enhance their data storage capabilities while maintaining high performance and efficiency.