74 Implementing the IBM Storwize V7000 with IBM Spectrum Virtualize V8.2.1
3.15.2  Combining FlashCopy and Metro Mirror or Global Mirror
Use of FlashCopy in combination with Metro Mirror or Global Mirror is allowed if the following 
conditions are met:
/SM590000A FlashCopy mapping must be in the idle_copied state when its target volume is the 
secondary volume of a Metro Mirror or Global Mirror relationship.
/SM590000A FlashCopy mapping cannot be manipulated to change the contents of the target volume 
of that mapping when the target volume is the primary volume of a Metro Mirror or Global 
Mirror relationship that is actively mirroring.
/SM590000The I/O group for the FlashCopy mappings must be the same as the I/O group for the 
FlashCopy target volume.
3.15.3  Planning for Metro Mirror and Global Mirror
Metro Mirror is a copy service that provides a continuous, synchronous mirror of one volume 
to a second volume. The systems can be up to 300 kilometers (186.4 miles) apart. Because 
the mirror is updated synchronously, no data is lost if the primary system becomes 
unavailable. Metro Mirror is typically used for disaster-recovery purposes, where it is 
important to avoid any data loss.
Global Mirror is a copy service that is similar to Metro Mirror, but copies data asynchronously. 
You do not have to wait for the write to the secondary system to complete. For long distances, 
performance is improved compared to Metro Mirror. However, if a failure occurs, you might 
lose data.
Global Mirror uses one of two methods to replicate data. Multicycling Global Mirror is 
designed to replicate data while adjusting for bandwidth constraints. It is appropriate for 
environments where it is acceptable to lose a few minutes of data if a failure occurs. 
31 - 40 1 MiB 4 16
41 - 50 2 MiB 8 32
51 - 60 4 MiB 16 64
61 - 70 8 MiB 32 128
71 - 80 16 MiB 64 256
81 - 90 32 MiB 128 512
91 - 100 64 MiB 256 1024
101 - 110 128 MiB 512 2948
111 - 120 256 MiB 1024 4096
121 - 130 512 MiB 2048 8192
131 - 140 1 GiB 4096 16384
141 - 150 2 GiB 8192 32768
User percentage Data copied per
second
256 KiB grain per
second
64 KiB grain per
second