Which one is the largest space ?

petabyte is the largest space.

Enterprise storage systems are starting to leave the terabyte behind, moving into petabytes and toward the exabyte stage. A petabyte (PB) is 1015 bytes of data, 1,000 terabytes (TB) or 1,000,000 gigabytes (GB).

If you want an even larger measurement of data storage, there's the exabyte, which is 1,000 times larger than a petabyte. ... Then you get to the zettabyte, which is 1,000 times larger than an exabyte, which is 1 million petabytes.

$94 trillion petabyte. IBM is celebrating the 55th anniversary of the first hard drive. At the time, this was a breakthrough that would change the path of technology. Compare that to being able to get a petabyte of storage for $117,000 and store it in a single rack.