As discussed in today's meeting between serviceops-collab and releng, at this point we don't really see an advantage of having phab2001 around as a warm standby.
If we had to fail-over to codfw we would use phab2002 for that and the hardware phab2001 can start to be decom'ed.
So this is a decom subtask for that as we will need one anyways later once it goes to dcops.