| Most HP-UX system administrators employ a dual backup strategy. The first is to use the make_recovery command of Ignite-UX to create a bootable backup tape of their root volume (make_recovery is covered in Chapter 10). Secondly, a backup program is used to back up the balance of data on the system. In this chapter I'll give an overview of several backup commands. I won't cover any advanced backup programs such as HP's OmniBack. Advanced backup tools, however, can make tasks such as centralized backup and overall management of backup much easier. Here is a brief overview of backup programs I'll cover in upcoming sections: | tar | tar is widely considered the most portable of the backup and restore programs. tar is the most popular generic backup utility. You will find that many applications are shipped on tar tapes. This is the most widely used format for exchanging data with other UNIX systems. tar is the oldest UNIX backup method and therefore runs on all UNIX systems. You can append files to the end of a tar tape, which you can't do with fbackup.When sending files to another UNIX user, I would strongly recommend tar. tar is as slow as molasses, so you won't want to use it for your full or incremental backups. One highly desirable aspect of tar is that when you load files onto a tape with tar and then restore them onto another system, the original users and groups are retained. | | cpio | cpio is also portable and easy to use, like tar. In addition, cpio is much faster than tar -not as fast as fbackup, but much faster than tar. cpio is good for replicating directory trees. | | fbackup | fbackup is the utility used by SAM. It has a lot of functionality associated with it, such as specifying whether the backup is full or incremental, different levels of backup, files and directories to be included or excluded, support for a graph file which specifies files to be included and excluded, and other advanced features. fbackup is an HP-UX-only utility, and tapes can be read using frecover on HP-UX systems only. | | dd | This is a bit-for-bit copy. It is not smart in the sense that it does not copy files and ownerships; it just copies bits. You could not, therefore, select an individual file from a dd tape as you could with frecover, tar, restore or cpio. dd is mainly used for converting data such as EBCDIC to ASCII. | | dump | dump is similar to fbackup. If you use fbackup on HPUX, you will see much similarity when you use dump. dump provides the same-level backup scheme as fbackup and creates /var/adm/dumpdates, which lists the last time a file system was backed up. restore is used to read information backed up with dump. dump, however, works only with HFS file systems and not VxFS, and it assumes that you are using a reel tape. |
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