The full form of PB is Peta Byte

A petabyte is a measure of memory or data storage capacity that is equal to 2 to the 50^th power of bytes. There are 1,024 terabytes (TB) in a petabyte — or 1 million gigabytes (GB) — and approximately 1,024 PB make up one exabyte.

Petabytes are not suited to traditional data backups, which have to scan the entire system every time a data backup or archiving job occurs. Traditional network-attached storage (NAS) is scalable and capable of handling petabytes of data, but it can take too much time and use too many resources when going through the system’s organized storage index.

Comparing memory and not storage, a typical laptop or desktop computer contains 16 GB of random access memory (RAM). A top-end server can contain as much as 6 TB of RAM. That means it would take 170 top-end servers — or roughly 61,000 desktops — to add up to a single petabyte of RAM.

For another example of how large a petabyte of storage is, a typical DVD holds 4.7 GB of data. That means a single terabyte of storage could hold 217.8 DVD-quality movies, while a single petabyte of storage could hold 223,101 DVD-quality movies.