You can use the IBM® FlashCopy® and Metro Mirror
and Global Mirror Copy Services functions for SAN Volume Controller across
the host storage systems to help simplify operations.
The following requirements and restrictions apply to FlashCopy, Metro Mirror, and Global Mirror
functions:
- If you require concurrent read/write access to both the source
and target volumes, be sure that the source volume resides on a different
host system than the target volume. A copy operation from a source
volume to a target volume that is on the same host system creates
a target volume with the same identification as the source volume.
The host system sees two identical volumes.
- When the copy operation creates the same identification for the
target volume as for the source volume, you cannot distinguish one
from the other. Therefore, you might not be able to access the original
data.
- The target volume and the source volume can be on the same host
system for a Metro Mirror, Global Mirror, or FlashCopy operation only under the following
conditions:
- For the IBM AIX® operating system, when the host is using
a logical volume manager (LVM) with recreatevg command.
- For Hewlett-Packard (HP), when the host is using LVM with the vfchigid
-f command.
- For the AIX and Sun operating
systems, when the host is not using an LVM.
- For host systems that run the VERITAS Volume Manager, the SAN Volume Controller sets a bit in the inquiry data that enables the VERITAS
Volume Manager to distinguish between the source and target virtual
disks (VDisks) for those mapping states where the source and target
VDisks might be identical copies.
- For any host system, when the host system can distinguish between
a source and a target volume that has the same identification.