From my point of view this isn't something that belongs in an Enterprise Data Migration Strategy. It's not that I don't think that keeping the volume of data to be migrated down has merit. I don't need convincing that involving more data increases the cost and heightens the risks of overruns or impacts outside of the organisation's walls but, even more importantly, I don't think it's my place to be mandating a minimum data approach in a blanket fashion. For me, each of our data migrations will have different needs, different profiles and different levels of data to be migrated. And let's not forget that it's the business, not the technical staff, who should be making the calls about how much data to migrate!
This discussion got me thinking. There is value in keeping migration data volumes low so how could I, through the strategy, encourage this behaviour without presupposing it was the right course of action for each migration project? After some thinking I've landed on updating the data migration strategy to include a new principle:
Expanding this a little, I see two key points that should be considered in finding this appropriate level of data.
- Firstly, a default position of migrating all available data is not where we should start.
- Secondly, and following on from this, don't just ask the question "how much data do we need to migrate", but instead try the question "how much data can we afford not to migrate - what data can we leave behind?"
The unanswered question here is how does the business decide on the appropriate level of data? I've used various techniques to help in the past and I've some new ideas as well, but that's a discussion I'll leave for another blog post.