We need to migrate all In-Progress workflow from Moss 2007 to SP 2013. Application is very critical for customer, They dont want to lose current workflow state during migration.<o:p></o:p>

 Over View of Application (Moss 2007):-

Existing System have one Library where almost 40K records exists. (In Progress workflow number is 250+).<o:p></o:p>

Task List having 100K records.

Each workflow item has 7-8 steps for approval. From the first to last step Workflow status is IN PROGRESS.

Migration Approach:-

Manual DB Detach -> Attach -> Mount. 

Please suggest, If any one did Custom VS Workflow(in progress) Migration or suggest any feasible approach or any tool support for the same.<o:p></o:p>