Not accurate in databases (where master only means authoritative source), not accurate in hard drives (master only denotes precedence), not accurate in hardware clocks (used to determine sync hierarchy - see NTP for a much better convention). "Master" only makes sense in a system where a component is delegating tasks and controlling one or more "slaves", and even then something like "controller" is clearer.

- Master database tells the slaves what to write

But that's only an ad-hoc state of affairs; the only thing telling a database (in postgres, at least) that it's a replica is that it has a couple of settings telling it what to replicate from, and if you remove those and restart (or otherwise trigger a failover), the replica becomes the new master.

In slavery, the only correct thing for a master to do is to abdicate power, and it is not wrong for a slave to reject that power relationship.

When people use it for hardware and software, there's a tacit understanding that the power relationship must be preserved.

These two are diametrically opposed.

> In slavery, the only correct thing for a master to do is to abdicate power, and it is not wrong for a slave to reject that power relationship.

Once that happens, they are no longer master and slave, of course.