Editing ISO 9660 (section)

=== Volume size ===
An ISO 9660 volume can be up to 8 tebibytes (nearly 8.8 terabytes) in size, owing to the 32-bit sector count for the volume size, and its allocation unit size which spans 2048 bytes, matching a logical sector on optical discs. The highest number representable in a 32-bit field is 2<sup>32</sup>-1, limiting the volume size to (2<sup>32</sup>-1)×2048 bytes. "Logical" means it is the sector size exposed to the operating system, not necessarily the physical sector size on a disc. DVD and Blu-ray discs have maintained the logical sector size of the CD-ROM, 2048 bytes, to try to maintain reading compatibility with computers and software predating them.