for 2 years if you decide to leave the job on peaceful reasons. that is, you will have to spend 2 years outside Qatar before you can get work here again, unless the company agrees to give you NOC (which very rarely happens).
however, if the cause of the resignation is something criminal (just talking theoretically here), you may be looking at a GCC-wide ban since you will fail the CID clearance.
by the way, the pay seems to be very motivating. and perhaps someone else will share info on the single room accommodation.