Storage is uncountable. You cannot say a storage. A unit of storage is usually called a store, which is countable, of course. It can also be called a storage unit. For example:
The storage for a Harvard architecture computer comprises an
instruction store and a data store.
or
I placed my clothes into storage. We hired a storage unit from Honest John's Storage.
(Both in computing and also physical storage, you can use either store or storage unit as you see fit. The former inclines somewhat to talking about storing in abstract, the latter to a physical location. Unit can, less commonly, be substituted with similar words, such as device, locker, location, ....
Edit: This is the situation for British English and US English the situation may be more complex in Australian English, about which I'm not qualified to comment.
Your search for a rule is admirable, but alas! doomed to failure.
- The plural of fish is fish. Unless you're differentiating between species:
The smaller fishes are more affected by ocean warming than the larger.
Or if you are a mafioso, in which case you say
Vinnie sleeps with the fishes.
Of if you're a theologian discussing the miracle of
the loaves and fishes.
Different species form plurals in unpredictable ways. Both tuna and salmon are their own plurals. Species that end in -ing, like the ling form their plurals by adding a final s, except for grayling and herring. You just have to look it up here. However, if the fish name is the name of a special at your restaurant, you might hear a waitress call out
I need two salmons and three tunas!
She means two orders of the salmon dish and three of the tuna dish.
No matter how many you have in a bowl, you only have fish, never fishes.
- Cakes is the plural of cake. It never means pieces of cake:
Some cakes have frosting; others have icing.
- The plural of fruit is fruits, but only when you're talking about different varieties:
Some fruits -- bananas, apples, kiwis -- are good for you. The rest are not.
You always eat some fruit.
- Drinks are the typical nonountable nouns, except when you're talking about varieties or individual servings:
Whiskeys are either blended or single-malt.
Give me two whiskeys, two scotches, two beers.
Waters has an additional plural as the naturally occurring water in a location, so during your vacation, you
take the waters at the spa at the hot springs
- Cheese follows the variety rule. If you have three cheeses on your cheese plate, then you have three different types of cheese, even when you have six pieces of cheese total. Same with milk:
I make three different nut milks in my blender -- walnut, hazelnut, and almond.
The plural of beef is beeves, but it's only used to describe individual animals, meat-on-the-hoof, so to speak.
Best Answer
The dictionary erred when giving that example for the use as a countable noun. The example clearly is using it in a general sense rather than as a concrete, countable noun. We can change the example to fit as a countable noun by either adding an article or by making 'society' plural. "Good writing still has a place in contemporary societies." "Good writing still has a place in a contemporary society." As we can see, this changes the meaning. The word 'contemporary' has nothing to do with the countability of 'society'.