
Metro Mirror and Global Copy
From a local data migration point of view both methods are on par with each other, with Global Copy having a smaller impact on the subsystem performance and Metro Mirror requiring almost no time for the final synchronization phase. It is advisable to use Global Copy instead of Metro Mirror, if the source system is already at its performance limit even without remote mirroring. Figure
Host
Host
Host
Initial Copy Continuous updates
Stop applications Final synchronization
Restart
Using new copy
Figure 15-6 Migration with Metro Mirror or Global Copy
The remote copy functionality can be used to migrate data in either direction between the Enterprise Storage Server (ESS) 750 or 800 and the new DS8000 and DS6000 storage systems. The ESS E20 and F20 lack support for remote copy over Fibre Channel and can therefore not be mirrored directly to a DS6000.
Combination of Metro Mirror and Global Copy
A cascading Metro Mirror and Global Copy solution is useful in two cases:
The source system is already mirrored for disaster tolerance and mirroring is mandatory for production. Then a Global Copy relationship can be used to migrate the data from the secondary volumes of the Metro Mirror pair to the new machine.
Data must be migrated from an older ESS E20 or F20. Here a Metro Mirror using ESCON connectivity is used to mirror the data to an intermediate ESS 800, which in turn will copy the data to the DS8000 with Global Copy.
Figure 15-7 shows the setup and steps to take for this method.
Host
Host
Host
Intermediate Device
Initial Copy
Continuous updates
Metro Mirror | Global Copy |
Stop applications
Final synchronization
Restart
Using new copy
Figure 15-7 Migration with Metro Mirror, Global Copy and an intermediate device
296DS6000 Series: Concepts and Architecture