From the book OKB MiG, page 138/139: Canopy consisted of two-piece transparency in frame and mounted on rails for aft-opening.

To end the discussion, in MiG – Fifty Years of Secret Aircraft Design, page 87, is a nice picture of a MiG-9 with a sliding canopy.

Since I started the thread.. here’s the photographic evidence coming from

http://walkarounds.airforce.ru/avia/rus/mig/mig-9/