Reyanna is right. It is certain that, in Russian,
Pasha is the diminutive of
Pavel which corresponds to
Paul (Greek Paulos or
Pavlos). The first sylable is stressed and both "a" should be heard as in "father".
"
Pasha" (the stress on the second sylable, the same "a") has nothing in common with the Russian name
Pasha. Local governers in the Ottoman empire were titled pasha (
Ali pasha,
Suleyman pasha etc.)
Pasha was not a personal name. Rather, it was something like general or colonel. That Turkish word pasha originates from Persian, obviously. The etymoligy given
Pavlos (pasha < bash-a ) cannot be explain in Turkish. On the other hand, there is also the word "padishah" in Turkish which was borrowed from Persian. So, the explanation of Oxf. Engl. Dict. for pasha is also weak.
Pasha must have some other origin in Persian.