Implementing point-in time copy solutions on a primary host


Implementing point-in time copy solutions on a primary host
Prev	When to use point-in-time copies	Next

Figure: Using snapshots and FastResync to implement point-in-time copy solutions on a primary host illustrates the steps that are needed to set up the processing solution on the primary host.

Figure: Using snapshots and FastResync to implement point-in-time copy solutions on a primary host

Note:

The Disk Group Split/Join functionality is not used. As all processing takes place in the same disk group, synchronization of the contents of the snapshots from the original volumes is not usually required unless you want to prevent disk contention. Snapshot creation and updating are practically instantaneous.

Figure: Example point-in-time copy solution on a primary host shows the suggested arrangement for implementing solutions where the primary host is used and disk contention is to be avoided.

Figure: Example point-in-time copy solution on a primary host

In this setup, it is recommended that separate paths (shown as 1 and 2) from separate controllers be configured to the disks containing the primary volumes and the snapshot volumes. This avoids contention for disk access, but the primary host's CPU, memory and I/O resources are more heavily utilized when the processing application is run.

Note:

For space-optimized or unsynchronized full-sized instant snapshots, it is not possible to isolate the I/O pathways in this way. This is because such snapshots only contain the contents of changed regions from the original volume. If applications access data that remains in unchanged regions, this is read from the original volume.