Length of Sukka walls

I want to get permanent walls for our pergola made of canvas that cab be rolled up and down and serve as walls for a Sukka a well. What is the required length for a wall so that the Sukka will be Kosher?

A Sukkah must be 7 Tefachim wide, which is 56 cm according to the more lenient opinion. Bear in mind that canvas Sukkot may present a Halachic problem.The Shulchan Aruch rules that one should not use a canvas-walled Sukkah because it may not remain properly in place. There is a dispute among authorities what the concern is. Most understand that if the wall blows in the wind it is invalid. The minority opinion rules that it becomes invalid only if the wind causes it to blow apart or that it blows in a way that huge gaps remain- so that no wall remains in place. Either way, use of a cloth –walled Sukkah is highly problematic and should be avoided.