Critical data changes occur throughout the day, and this data needs to be protected against damage, loss, or lack of availability. Dell MD3600f/MD3620f (MD36X0f) series of storage arrays provide the critical and necessary protection of your data assets.
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide Dell MD36X0f Remote Replication (RR) Overview Remote Replication (RR) is the MD36X0f array feature that provides the ability to remotely replicate data from one MD36X0f storage array to another. RR is an optional premium feature that requires activation, configuration, and in normal replication operations, administration and control;...
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) •...
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide virtual disk to a primary role. Hosts will then be able to read and write to the newly promoted virtual disk and business operations can continue. Replication Repository A replication repository is a special virtual disk in the storage array created as a resource for the primary MD36X0f storage array whenever Remote Replication is used.
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide Figure 1: Examples of Replication Relationships Data Replication Modes Data replication between the primary virtual disk and the secondary virtual disk is managed by the MD36X0f storage arrays and is transparent to host machines and applications.
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Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide Figure 2: Synchronous Replication Mode Host sends Write Request Primary (local) controller at the local site takes in the request, and stores the request in the Replication Repository Primary (local) controller writes the data into the primary virtual disk...
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide Asynchronous Replication Asynchronous replication removes the restriction that the remote write has to complete along with the local primary write. The MD36X0f will separately queue each remote write to allow the local primary write completion to signal Host I/O completion (thus no waiting for the remote write to complete).
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide NOTE The write completion signal is sent in Step 3 as opposed to Step 7 in synchronous mode as shown in Figure 3 Asynchronous replication is usually required when the remote site distances are greater than 10KM and cannot tolerate slowing the host application I/Os by waiting for remote write completions.
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide Figure 4: Asynchronous Mode with Write Order Consistency A second feature of AWOC is that if a single replicated pair goes out of synchronization due to a failure to write to the remote virtual disk, remote write I/Os of the entire consistency group are suspended.
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide RR Suspend and Resume with Delta Log Resynchronization It is important to be able to size the communications link for throughput and for IOPs. Peak period measurement for the application’s set of virtual disks is necessary in order to determine the bandwidth required for remote replication.
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide Database Consistency and Database Hot Backups After suspending AWOC for database virtual disk replication, and, if a disaster occurs while resuming RR then the remote database virtual disks are not recoverable. This is due to the delta log processing of missing I/O in non-original write order.
Dell PowerVault MD3600f/MD3620f Remote Replication Functional Guide Summary Dell PowerVault MD36X0f Remote Replication option provides a robust set of features to implement disaster recovery solutions. Features include SAN based replication between multiple MD36X0f storage arrays in any combination of primary or secondary replication roles and dynamic replication mode switching.