In UNIX, the backup system uses an operating system utility, such as tar (Berkeley UNIX) or cpio (System V), to create checkpoints. Both cpio and tar are limited to handling files that fit on a single tape. Because checkpoints of larger databases abort at the end of the first tape, you must estimate both the checkpoint size and the tape capacity before checkpointing these databases. If you estimate that the checkpoint exceeds the tape size, follow instructions in Checkpointing to Multiple Tapes in UNIX.