CX4 mirror question

Hello,

I would like to ask. If we have for one customer synchronous mirror between two CX4 and they want to test the target site.

They don't want to switch direction, so no Promote. 2 servers, each server has own consistency group. Source servers will be offline during the test.

I wanted to know, when the target LUNs will be again read/write? Is only fracture enough or the secondary image needs to be removed from the mirror itself?

For me is important how to do it. If only fracture of CG and mapping of target LUNs to target servers or remove all secondary images, or even remove images and whole mirror from on CX4 to another CX4 and after test recreation of everything.

Because with the high number of used LUNs it will be crazy to create everything again in unisphere

Thank you