Brocade Communications Systems StorageWorks 4400 - Enterprise Virtual Array Manual de usuario descargar pdf (Pagina 24)

Continuous Access replication tunnels

Replicated EVA Vdisks (copy sets) are grouped in DR groups. When a DR group is created, a relationship is

established between a source and destination-managing EVA controller. Data is replicated from the source

to the specified destination controller through a path. This path is called a data replication tunnel (DRT).

There is one tunnel per source/destination controller pair. To ensure I/O consistency, Continuous Access

uses only one tunnel per DR group. These resources are limited; therefore, it is important to configure data

replication adequately to scale the number of tunnels to avoid possible resource contention with large DR

groups under heavy write traffic. As shown in Figure 15, with two or more DR groups, the EVA pair

establishes a symmetric relationship by default (using the same controller, A or B on source and destination

EVAs); which limits the number of concurrent tunnels to two.

Figure 15. Symmetric versus Asymmetric tunnels configuration

However, using an asymmetric configuration whereby a DR group is using a different controller on the

source and destination EVA (for example, DR group source members are online to EVA-1/Controller A and

destination members are online to EVA-2/Controller B), you can establish up to four concurrent tunnels

between a source and destination EVA.

Host port preferences are set to defaults during controller initialization but can be changed using HP

Command View EVA 9.0 and later. Manually setting host port preferences should be done carefully and

only when absolutely necessary. Default settings are appropriate for most use cases. For more information

see the HP StorageWorks Continuous Access EVA Implementation Guide.

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Brocade Communications Systems StorageWorks 4400 - Enterprise Virtual Array Manual de usuario Pagina 24