In the basic configuration illustrated by Figure 1,
the PPRC (Metro Mirror) pair go into a duplex pending state while
the tracks associated with the FlashCopy® relationship
are copied to the PPRC secondary device. With a different configuration,
you can preserve mirroring, that is, keep the PPRC relationship in
a full duplex state, during the FlashCopy.
This is illustrated in Figure 1.
Figure 1. FlashCopy Target as PPRC Primary
with Preserve Mirroring
In this illustration, there are two PPRC pairs: Local A is a PPRC primary device associated with Remote A and Local B is a PPRC primary device associated with Remote B.
The requirements for this configuration are:
- Both Local A and Local B must be Metro Mirror primary devices in full duplex mode with links established and available
- Remote A and Remote B must reside in the same Storage Facility Image (SFI)
- Local A and Local B can be the same device for an operation at the data set level
- The required microcode level must be installed in both the local and the remote storage control units
Preserve Mirror operations can be at the full volume or data set
(track) level. Preserve Mirror can be used in combination with:
- Incremental FlashCopy (unless the request is attempting to take an increment using Preserve Mirror on a relationship that was established without Preserve Mirror)
- COPY, NOCOPY, or NOCOPY to COPY
- FlashCopy consistency groups
- Fixed block devices
Preserve Mirror cannot be used in combination with:
- Commit
- Revert
- Fast Reverse Restore
- Global Mirror
- Global Copy
- Cascading PPRC
To establish a FlashCopy Preserve Mirror relationship, you issue a FlashCopy FCESTABL command from the Metro Mirror primary device (Local A) to another Metro Mirror primary device (Local B) with the PRESERVEMIRROR(REQUIRED) or PRESERVEMIRROR(PREFERRED) options. See FlashCopy establish (FCESTABL) command for more information on the command.