What are petabytes and just how big are they?

Enterprise storage is moving from tera to peta, but what do the terms mean?

Numbers against dark background

As the amount of data produced by businesses is constantly increasing, so is the demand for more data storage. That is why large measurement concepts which once might have seemed purely hypothetical, such as yottabytes, are now considered not too from reality after all.

Such is the case with petabytes. At one quadrillion bytes, saying that they contain quite a bit of data might be an understatement. In fact, the amount is rarely even considered by the average consumer, who will likely never need that much storage in their lifetime. In fact, most consumer hard drives rarely exceed the 4TB mark, with most personal computers ranging from 250 to 320GB of storage.

Petabyte-scale equipment is produced by a number of tech giants, including IBM, HPE, and Dell EMC, and is usually used in the infrastructure of major enterprises, especially for storage contained in large data centres which handle Big Data workloads. These could include research institutions and bigger universities, as well as industries specialising in the collection and analysis of massive quantities of data, such as the financial or pharmaceutical sector.

Such was the case with pharmaceutical molecule designer Schrödinger, which last year announced it was using Nvidia’s GPUs to generate and evaluate petabytes of data required in the process of discovering new drugs. Prior to the pandemic, pharmaceutical companies would normally invest billions of dollars to develop drugs, only to see the vast majority of them fail during or before clinical trials. With the help of Nvidia’s GPUs, Schrödinger would have more computing power to assess the potential pharmaceutical properties of a larger number of molecules.

Even if you're not in the market for a huge data centre just now, it's still worth familiarising yourself with the idea of petabyte storage, as your own computer could be sporting it sooner rather than later.

Consider that when floppy disks were first popularised in the mid-1970s, they typically only held 360KB data. By the time they were phased out in the late 90s, that had grown to 240MB.

Skipping forward a few decades, the latest HP EliteBook, Dell Latitude and iMac Pro have 16GB, 256GB and 1TB onboard storage respectively. Not long ago, these capacities in consumer devices even in standard enterprise data centres would have been unthinkable. And this is an area where progress marches ever forward, so don't be surprised to see this kind of capacity headed to laptops and desktops within the next 20 years.

Mega, giga, tera... what's the difference?

Every measurement of storage is made up of bytes and each byte is made up of 8 bits, right at the bottom of the storage pile. From byte, we move up the size ladder, with kilobyte next in line, followed by megabyte, gigabyte, terabyte, petabyte, exabyte, and the unfathomably large zettabyte and yottabyte.

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In order to convert from a lower metric to a higher, the rule is to multiply the number by 1,024 - so 1 terabyte is the same as 1,024 gigabytes.

So for example: 1 GB = 1,024 MB = 1,048,576 KB = 1,073,741,824 B.

That may sound strange if you've always been told that a kilobyte was a thousand bytes, and a megabyte a thousand kilobytes. The confusion is in part due to the use of binary in computers instead of decimal - 1,000 would be 1111101000 in binary, which isn't a convenient group size to use for a storage metric.

The use of 'kilo' is also confusing, given that a kilometre is 1,000 metres, not 1,024. In fact, in 1998 the International Electrotechnical Commission introduced new standardised prefixes, including "kibibytes" instead of kilobytes and "mebibytes" instead of megabytes... but they never quite caught on.

Here's a comparison between the various sizes:

MetricExponentSize (bytes)
Byte (B)11
Kilobyte (KB)1024^11,024
Megabyte (MB)1024^21,048,576
Gigabyte (GB)1024^31,073,741,824
Terabyte (TB)1024^41,099,511,627,776
Petabyte (PB)1024^51,125,899,906,842,624
Exabyte (EB)1024^61,152,921,504,606,846,976
Zettabyte (ZB)1024^71,180,591,620,717,411,303,424
Yottabyte (YB)1024^81,208,925,819,614,629,174,706,176
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