primary instance conversion docs ambiguous

[anarcat]

the primary instance conversion procedure in the evacuating node admin docs is ambiguous. it seems to say that, to evacuate a node, you first need to switch all the primary instances to their secondaries:

There are two steps of moving instances off a node:

• moving the primary instances (actually converting them into secondary instances)
• moving the secondary instances (including any instances converted in the step above)

Then it says:

For [the primary instance conversion] step, you can use either individual instance move commands (as seen in Changing the primary node) or the bulk per-node versions; these are:

$ gnt-node migrate NODE
$ gnt-node evacuate -s NODE

I read this as gnt-node migrate NODE and gnt-node evacuate -s NODE as being equivalent. But this is what gnt-node --help actually says:

    evacuate           - Relocate the primary and/or secondary instances from a node
    migrate            - Migrate all the primary instance on a node away from it

And digging a little deeper, in gnt-node evacuate --help, we see:

--secondary-only, -s    Evacuate secondary instances only (applies only to

Which means that this:

gnt-node migrate NODE

migrates all primary nodes away from the node, and this:

gnt-node evacuate -s NODE

will migrate all secondary isntances from a node.

Now, this seems like the opposite of each other. In any case, this documentation should be clarified.

Because I can't seem to have patches accepted in this community (see this discussion for the gory details) I am deliberately not providing a patch for this, so that some one else can actually fix this problem.

But the fix should be trivial enough that this shouldn't be necessary.