Suppose a large file were being written. When the current track fills up, the computer switches to another read-write head, an electronic operation which is almost instantaneous, and continues writing on the next track in the same cylinder. Of course, it may run out of room even then, in which case it can switch to the next cylinder and continue there. UNIX BSD4.3 clumps cylinders into cylinder groups to further isolate parts of the disk and minimize seek time. Each cylinder group has its own private free sector list.

Very large files such as huge databases may not fit entirely on one disk drive, in which case they may be continued on another drive. Specialized database management software helps the operating system with their maintenance.