Managing Bricks
Brick is the basic unit of storage, represented by an export directory
on a server in the storage cluster. You can expand, shrink, and migrate
volume of you cluster, as required, by adding new bricks, removing
bricks, and migrating bricks.
Note: You need to add at least one brick to a distributed
volume, multiples of two bricks to mirrored distributed volumes,
multiples of four bricks to striped distributed volumes when expanding
your storage space.