Ubuntu is making a change in the way the OS reads the file size in the future release of the distro, that is in Ubuntu 10.10. From Ubuntu 10.10, the base-2 system that is currently in use is going to be replaced by base-10 system.
Right now in Ubuntu, 1 KB is represented as 1024 B. This system is what is called the base-2 system but violates the IEC naming standard. The base-2 system is however, not used by various hardware manufacturers (you might have noticed that when you plug in your 500 GB external hard disk, it is shown as 466 GB) and some applications. So, the SI naming system (base-10 units) will appear in Unbuntu 10.10 to represent the network bandwidths, disk sizes and so on.
The base-10 system was introduced in one of the Lucid daily builds. But since the Lucid release is only a few weeks away, other applications which rely on the base-2 system cannot be changed in time. As a result, base-2 system will continue to be used in Lucid and the base-10 system will be introduced in the next version after Lucid, i.e. Ubuntu 10.10.
From Ubuntu 10.10, base-10 unit based on SI naming system will be used in network bandwidth, disk sizes etc. However for RAM size, base-2 units will still be used. However, the base-2 units will use the IEC naming system.
Here is a what the IEC and SI standards are like:
- IEC standard for base-2 units:
- 1 KiB = 1,024 bytes (Note: big k)
- 1 MiB = 1,024 KiB = 1,048,576 bytes
- 1 GiB = 1,024 MiB = 1,048,576 KiB = 1,073,741,824 bytes
- 1 TiB = 1,024 GiB = 1,048,576 MiB = 1,073,741,824 KiB = 1,099,511,627,776 bytes
- SI standard for base-10 units:
- 1 kB = 1,000 bytes (Note: small k)
- 1 MB = 1,000 kB = 1,000,000 bytes
- 1 GB = 1,000 MB = 1,000,000 kB = 1,000,000,000 bytes
- 1 TB = 1,000 GB = 1,000,000 MB = 1,000,000,000 kB = 1,000,000,000,000 bytes