how to failover in log shipping?
I suspect he's talking about doing the failover manually.
If, as you say, your Data Centre gets totalled, then you're not going to be able to get anything back from your old, Primary server.  It's toast.
That's probably why he leads with:

Unlike other high availability and disaster recovery technologies ...

These other technologies ship logs around much faster so that there's no &quot;trailing edge&quot; to worry about.