The ideal lumber storage rack for each shop will be different due to the layout of the shop, the type of materials used and the size of the shop.
One of the keys. . to an efficient shops storage system is how you run your shop. If you have a production shop that depends on material flowing through smoothly then you should have lumber and plywood stored in different places along the production line.
Full sheets of plywood and lengths of lumber should be in the rough cut area, parts cut to size in the production area and prefinished parts in the assembly area.
A small shop. ., making one or two items at a time, would be better served by mobile storage to move around the shop as needed.
In my shop. . I've found that I must stay on top of the days storage needs or I soon find myself continually moving cutoffs and parts out of my way in order to get my work done.
Lumber storage. . isn't much of a problem other than taking up space. I store it on horizontal racks with cut off pieces going back on the same pile. Ideally, horizontal racks should have a stiff bottom board to stack your lumber on. This keeps lumber from bowing due to long spans being unsupported. It also allows short pieces to be put back without falling between supports.
I like to store plywood. . vertically on edge. Normally in my shop I keep several sheets on hand. By storing these vertically I can pull one piece without having to move half a dozen sheets or more to get to it. This saves a lot of work and helps save the plywood surface from scratches.
If you decide to try vertical storage make sure the sheets are vertical and not leaning. Unsupported sheets that are leaning will bow.