I have seen 0.5, 2 and 5 meters. As I understand, it depends on whether this is configured as the first or subsequent shelf (i.e. whether this is controller-to-shelf or shelf-to-shelf). I must admit I have not used NetApp quoting tool for ages, so I do not know whether this is possible to explicitly select cable length when quoting shelf.
But you always should be able to add additional cables as single parts.
10 and 20 meter cables also exist according to the system configuration guide.
Default 2 meter cables are quoted, even for connecting shelves in the same stack. Just ask sales for the length you want/need. because sascables that are too long are not as easy to manage as fiber cables.
E.g. 0.5 meter for daisy chaining the shelves if you are directly below each other. For connecting to the controllers either 2 or 5 meters depending on the amount of shelves in the stack and the location of the controllers.