I am getting ready to do a big data migration. I am planning on doing an initial level 0, and then multiple level 1's leading up to the big day.
It doesn't make sense to me why you would do multiple level 1 copies because a level 1 does not copy files that have changed since the previous level 1. To do this you must use a level 2 copy.
I agree with the spirt, but I would rephrase it. :-)
A level 1 *does* copy all the files that have changed since the previous level 1. It's just that they are a subset of files modified since the level 0 which are copied as well.
So running a level 1 on the last day should take about the same amount of time whether any other level 1 copies had been run previously or not.
Agreed on the rest about 0/1/2 ndmpcopy, but for flexibility I do like rsync as an alternative. It's just how much power you can toss at it and how long you can wait for the file list when you've got millions of files.
Remember you don't have to move everything in one rsync command. Espcially if you have multiple clients, it may may sense to split it up into a few separate subtrees.