I'm moving a WordPress installation from one server to another. The IP address will change, but the URL will not, since I will redirect DNS.
The problem: while DNS changes propogate, people might end up at either installation.
That's fine for reading, but if they leave comments/register/etc on the old server, their comments/registration/etc will be lost.
Is there any way I can make WordPress "read only" on the old site?
I realize WordPress uses its database (MySQL in my case) for internal purposes, and I can't simply disallow database writes.
In other words, I want to disallow user-initiated database writes/changes, but nothing that will stop WordPress for working properly in read-only mode.
Ideally, each page on the old server would say something like:
"You are viewing this WordPress blog on an old server. Until you receive a DNS update with a new IP address for wordpress.foo.com, you can read articles, but cannot comment on articles, register as a new user, etc".