Petabyte Definition & Meaning

A petabyte is 10¹⁵ bytes of digital information. The unit symbol for the petabyte is PB. It is a measure of memory or data storage capacity.

There are 1,024 terabytes (TB) or approximately 1 million gigabytes (GB) in a petabyte. 1,024 petabytes make up one exabyte. A petabyte is not suited for traditional data backups. To get an idea of how large a petabyte of storage is, here are some examples:

• A typical DVD holds 4.7 GB of data, meaning a petabyte of storage could hold 223,101 DVD-quality movies.
• To store one petabyte of data, 745 million floppy disks would be needed.
• The Library of Congress holds over 20 petabytes of data.
• A petabyte’s worth of data stored in 1GB flash drives would stretch over 92 football fields.

For comparison, this chart details a petabyte’s place in storage capacity.

Petabytes and Pebibytes

A petabyte is sometimes defined as a 2⁵⁰ bytes. There are two different systems of measuring bytes: the Base10 SI system (SI) and the Base2 IEC (IEC) system. While 2⁵⁰ bytes is close to 10¹⁵, it is higher and has a different term pebibyte (PiB).

Computing is based on the binary system rather than decimal. At low levels, the SI and IEC terms are interchangeable. 10³ = 1,000 and 2¹⁰ = 1,024, so there is only slightly more than a 2 percent difference between the one kilobyte (1,000 bytes) and one kibibyte (1024 bytes). As storage systems are never run within 2 percent of their capacity, there is no operational difference between the two.

There is greater divergence, however, as we get into higher orders of magnitude. As shown in the table below, the percentage difference grows as the byte amount grows. Therefore, when specifying capacity of a large scale system, it’s important to not to combine the two different systems of counting data storage space.

Petabyte storage vendors

Vendors selling immense storage systems for those needing a petabyte’s worth of storage capacity include:

• Broadberry
• StoneFly
• Aberdeen
• SimplStor