The old five-drive NAS had been “migrated.” Every share had a note saying so. Then I rebuilt it by hand, put it back on the network, and compared what was on the drives to what had supposedly moved.
One share held 17.6 times more data on the drive than in its migrated copy. Another held 12.4 times more. A 168 GB share had only 398 MB migrated. In the end, migrations marked done were somewhere between 6 and 24 percent done.
The verification had only covered what was copied.
That sentence is the whole problem. Someone checked the files that arrived and found them correct. Nobody checked how many files should have arrived. The check passed, the label said done, and a lot of footage was one dying drive away from gone.
What I ask now
- What is the full list of things that should exist at the destination?
- Who made that list, and from what?
- Can I see a count and a total size from the source side, not only the destination?
- If the answer to the last one is no, it is not done.
A forgotten device turned up later in the same project, holding 13 TB. A 2 percent sample showed 24,043 of 24,068 files already safe elsewhere. That was a nice surprise, but only because I counted instead of assuming.
If a migration in your own world is marked complete, ask for the source-side number. It is a five-minute question and it has saved me weeks. The first week of how I work is mostly that question, asked politely, many times.