Concurrent

Concurrent operations
Enginuity versions 5567 or higher support concurrent primary devices (R11) that are configured with two R1 SRDF mirrors. Two R1 SRDF mirrors allow the R11 devices to be mirrored concurrently to two R2 devices that can reside in one or two remote Symmetrix arrays. Each R1 SRDF mirror is configured to a different SRDF group.

Note: The R11 devices have to be assigned to two different SRDF groups even if the two partner R2 devices reside on the same remote Symmetrix array.

Setting up a concurrent SRDF relationship
Setting up a concurrent SRDF relationship is a two-step process:
1. Create the initial R1 -> R2 pair between Symmetrix A and Symmetrix B.
2. Create the R11 -> R2 pair between Symmetrix A and Symmetrix C.

 


Concurrent SRDF topologies are supported on:

  • Fibre Channel
  • Gigabit Ethernet (GigE)
  • ESCON SRDF topologies


Basic concurrent SRDF solutions
Requires that each R1 SRDF mirror operate in the same primary mode, either both synchronous or both semi-synchronous, but allows either or both SRDF mirrors to be placed into one of the adaptive copy modes.

Setting up a concurrent SRDF relationship is a two-step process:
1. Create the initial R1 -> R2 pair between Symmetrix A and Symmetrix B.
2. Create the R11 -> R2 pair between Symmetrix A and Symmetrix C.


Advanced concurrent SRDF solutions
Supports one or both R1 SRDF mirrors of the R11 device operating in asynchronous mode.

  • Concurrent SRDF/S with SRDF/A

Concurrent SRDF/S with SRDF/A is an advanced concurrent SRDF solution that allows one R1 mirror of an R11 device to operate in synchronous mode and the other R1mirror to operate in asynchronous mode.

  • Concurrent SRDF/A

Enginuity versions 5875.135.91 and higher support another advanced concurrent SRDF solution, concurrent SRDF/A. This solution allows both R1 SRDF mirrors of the R11 device to operate in asynchronous mode. At any time, two SRDF/A sessions exist for the R11 device, one for each R1 SRDF mirror. You can manage these SRDF/A sessions using MSC.



Migration with concurrent SRDF
Concurrent SRDF provides the ability to replace an existing R1 or R2 device with a new device in an SRDF pair. During migration, a concurrent SRDF relationship is established to transfer data from an existing device to a new device using adaptive copy disk mode. After this data transfer, the existing device is replaced with the newly populated device in the SRDF pair.


Concurrent SRDF with independent consistency protection

  • You can leverage the independent consistency protection feature in concurrent SRDF solutions that use SRDF/S on both branches of the concurrent SRDF topology (SRDF/S/S).
  • This feature is based on Enginuity Consistency Assist and enables you to independently manage consistency on each concurrent SRDF branch.
  • If consistency protection on one SRDF group (branch) is suspended, consistency protection on the other SRDF group (branch) can remain active and continue protecting the primary site.


Concurrent SRDF with independent consistency assist feature is available with Enginuity versions 5874 and higher. The following options are available for managing consistency groups in a concurrent SRDF/S/S configuration:

  • Independent consistency group protection
  • Joint consistency group protection.


Benefits
The benefits of concurrent SRDF are:

  • Extended distance solution with SRDF/A
  • Support for device migration
  • Integration with ECA.