The behavior of filesystems and LUNs with respect to managing physical storage is different on
the 7000 series than on many other systems. As described in the Concepts page, the ZFSSA leverages a pooled storage model where
all filesystems and LUNs share common space. Filesystems never have an explicit size assigned to
them, and only take up as much space as they need. LUNs reserve enough physical space to write the
entire contents of the device, unless they are thinly provisioned, in which case they behave like
filesystems and use only the amount of space physically consumed by data.
This system provides maximum flexibility and simplicity of management in an environment when
users are generally trusted to do the right thing. A stricter environment, where user's data usage
is monitored and/or restricted, requires more careful management. This section describes some of the
tools available to the administrator to control and manage space usage.