v0.31:Using bins and barrels
Ordinarily, each item or stack (e.g. ≡Dwarven Ale Stew ≡) of items occupies one space of stockpile room. You can consolidate stockpile space by building bins and barrels that can hold many items at once. Barrels store and preserve food and alcohol; bins can store many types of smaller items, such as finished goods, metal bars, ammo, or gems. Building a steady supply of containers helps reduce the space you need for storage. See pots for a non-wood alternative to barrels for some uses.
 Food Storage
One thing to note about storing seeds is that bags are required to put seeds in. These bags will then be placed inside the barrel. Otherwise, the dwarves'll end up with one seed per tile - quite inefficient!
 Managing stockpiles directly
It is possible to set whether bins can be used in a stockpile with Block, ammo, gems, finished goods, cloth and leather stockpiles, and barrels are used for food stockpiles. Also by default, the stockpiles that use barrels or bins to store other items will permit a barrel or bin on each of their spaces; such a stockpile will claim an empty container whenever it doesn't already have one. You can override this by specifying the maximum number of barrels and bins that an individual stockpile is allowed to utilize, using → / and / to decrement and increment the limits.→ / . For barrels, and are used instead of C and V. By default, bins are used for Bar/
 Reserving containers for other tasks
"Reserved Barrels/Bins" is a global setting that reserves a certain number of barrels or bins, preventing them from being claimed by a stockpile until they are filled by a Workshop that requires their use. This feature is most often used to ensure that a fortress has ample empty barrels for the production of alcohol, although empty barrels are also necessary for other jobs. You can change this setting in the stockpile menu. If there are 5 reserved barrels, no stockpile will claim an empty barrel until you have at least 6 lying around. In this way you can ensure that jobs like making alcohol always have free barrels available.
In the case of barrels necessary for producing alcohol and dwarven syrup, they do not have to be located on a furniture stockpile. This is because the "Store Item in <container>" task only looks at furniture stockpiles for available containers. Normal production tasks behave as mentioned earlier, they will just grab the nearest barrel. You can exert some limited control over this by setting a number of reserved barrels; however, you cannot set where these barrels will be.
Though it is possible to reserve bins, there is no advantage in doing so, as no workshop tasks make use of empty bins.
 Barrel Reassignment Surgery
If you have a fixed number of barrels (possibly due to a lumber shortage because you're playing in a Fun place like the tundra) and your food stockpile is using too many barrels and you need some for booze, or if for some reason the opposite is true, you can force the dwarves through a series of steps to have the barrels switch from one stockpile to another. Assume you have too much barrelled food and you need barrels for booze. First, designate a small garbage dump zone nearby. Then set the maximum barrel limit on the food stockpile way down--possibly to zero. Don't worry, the existing barrels won't be dumped as a result. Now view a barrel and then once inside, view each individual food item and set it to for dump (but do not dump the barrel itself). The dwarves will take the food from the barrel and throw it into the garbage zone, and once the barrel is empty they will immediately move it to a furniture stockpile because the food stockpile barrel limit is exceeded already. Now you have a free barrel with which to brew. You can reclaim the food from the garbage dump now, and the dwarves will do what they can to store it. Be warned that this might end up being on the floor in the stockpile which could attract flies. Remember to set the barrel limit on the food stockpile back up to some reasonable level if you get your hands on some new barrels. See pots for a non-wood alternative to barrels for some uses.
 Barrel and bin material
Heavy barrels and bins slow down hauling, so it is wise to make them from light materials if possible. Even the heaviest types of wood are lighter than any metal (excluding adamantine) - the wood of feather trees is the best of all, but if you do not have access to it, cedar is the next best.