Currently a maximum of 8191 non-global zones can be created within a single operating system instance. "Sparse Zones", in which most filesystem content is shared with the global zone, can take as little as 50 MB of disk space. "Whole Root Zones", in which each zone has its own copy of its operating system files, may occupy anywhere from several hundred megabytes to several gigabytes, depending on installed software. The 8191 limits arises from the limit of 8,192 loopback connections per Solaris instance. Each zone needs a loopback connection. The global zone gets one, leaving 8,191 for the non-global zones.