[dboreham]

Three. So you can do maintenance on one while still having HA.

[naniwaduni]

No, that's still two. You don't do maintenance when you're not awake.

[anon73044]

I was expecting a "two is one and one is none" reference. Three keeps the investors happy in my case.

[paulddraper]

*Sometimes three.

Go back to two when maintenance is done.

[fizwhiz]

This guy SRE-s!