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.
I know the that native ndmpcopy in OnTap 7.1 can only do one level 1, and one level 2 for each level 0.
But I have read that if you get ndmpcopy or jnmdpcopy from ndmp.org that it supports multiple level 1 dumps based on the same level 0.
But I am getting the same errors I got with the native ndmpcopy when I use ndmpcopy and jndmpcopy from a unix host. I just grabbed the latest copies for ndmp.org yesterday.
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.
A level 1 copies files that have changed since the previous level 0. So if you do multiple level 1 copies, then you end up recopying a lot of files.
And as you have discovered, ndmpcopy doesn't like it when you try to do a level 1 copy on top of another one. You must go to level 2.
Here is what I have done:
Run a level 0 copy while the filer is still available to the users. For large copies, this may take many hours, maybe even more than a day.
Run a level 1 copy soon after the level 0 finishes. This will be much quicker, but may still take a few hours because it copies all files that changed since the START of the level 0 copy. The filer is still available to the users.
Start your downtime. Disable NFS, CIFS, etc on the filer. You may need to shut down or idle clients beforehand.
During the downtime run a level 2 copy that copies files that changed since the START of the level 1 copy. This should take considerably less time than the level 1 copy, minimizing your downtime.
Since most of us must schedule downtime in advance, the trick is to estimate how long the level 0 and level 1 dumps will run and start them so that the level 1 copy finishes as close as possible to the start of the downtime. If the level 0 copy finishes earlier than expected, then hold off starting the level 1 copy.
Since you are copying one source volume to multiple destination volumes, all on the same filer, I recommend running your level 0 copies sequentially, followed by your level 1 copies, and then the level 2s.
Steve Losen scl@virginia.edu phone: 434-924-0640
University of Virginia ITC Unix Support