1. Backing up VG00 using m_t_r is for disastor recovery, that is, loss of the boot disk(s). This only needs to be done when major changes occur to the operating system such as a patch bundle or new hardware is added or removed (disks, tape, memory, I/O). Run m_t_r about once a month depending on the volatility of your hardware.
But run a separate tape using fbackup for file/directory retrieval. This backup will be used far more often than your m_t_r tape as you don't (hopefully) have disasters every week. fbackup can be used to bakcup everything VG00, VG01, etc and is the most effective method for this task. If everything fits on one tape, great. If not, fbackup is smart enough to pause and request another tape and not to record accidently over the first tape.
2. One of the featiures of commercial quality backup programs is the creation of a complete index that is stored at the front of each tape. You don't have to do anything special--it's automatic with fbackup. If you need an electronic copy, just run:
frecover -I /var/tmp/myindex -f /dev/rmt/0m
Now tar, cpio, dump, pax, etc have no index at all. Instead, you run the utility asking for a list of all the files and the entire tape is read (could require hours) to report on the headers that were found. fbackup can create a complete index in a few seconds. tar, cpio, dump, pax, etc can also have multiple backups on the same tape--you'll never know about these unless you keep very careful records. tar even has the ability to append the same files to a single backup and unlimited number of times. While this seems like it might be useful, to recover a particular version based on date requires a perfaectly accurate list of all backups and the dates they were taken. Then count the number of copies of the file needed to get to the desired version, start tar, watch carefully as tar reports each time it restores the same file, then once you see the desired quantity, quickly kill the process so a later version doesn't get restored--but not too quickly because you may not finish restoring all of the desired file. See how easy that is?
In other words, you don't ever want to dump multiple backups on the same tape and fbackup prevents this from happening. Another advantage of the fbackup index is that you can retrieve a random file from anyplace on the tape in just a few minutes. The reason is that the index contains a setmark reference for every 'n' number of files (controlled by the configuration file, 200 files by default). These setmarks can be scanned at 100times normal tape speed so to reach file number 2005, frecover will scan past 10 setmarks, then slow to normal speed and search for the 2005th file.
And finally, the index for a given backup session is created on *every* tape needed for the backup. Suppose there are 3 tapes needed. The first is completed and a second tape is inserted. As mentioned before, fbackup looks at the header on the tape to make sure it is not tape #1, then writes more files, and repeats until all the tapes are recorded. However, the index is a list of *all* the files that were originally requested. Since 'things happen' during the long backup process, some files may disappear and the index is updated on the current tape accordingly (file ##### not backed up - not found).
The index is also updated at the start of each tape to indicate what was stored on the previous tape and where this new tape starts. This is very crucial for fast retrieval. On the last tape, the index contains the history of all previous tapes. So to restore an artbitrary file, put the *LAST* tape in, run frecover and it will report the required tape ("insert volume 2...") in order to restore the file(s). So even with 3 tapes to create a complete backup, only a few minutes is needed to reload any random file.
Treat Omniback the same way as fbackup. It will create it's own index both on the tape as well in it's own database. Omniback (or fbackup) can NEVER be used to reload a dead or replacement server in a disaster situation because it require HP-UX to run. So treat the disaster portion as a seaprate, specialized task and the daily/weekly backup of files/directories as your regular backup strategy.
Bill Hassell, sysadmin
