Tracy Johnson says and to which I respond with a plug alert and a
warning that this is getting long:
>I use Roadrunner (RR) myself. I've used Orbit in another life. I
>believe RR is faster and that is my preference. Primarily because is
>that RR places the directory at the beginning of the tape (set) whereas
>Orbit places it at the end of the tape (set). Orbit will also let you
>have it on a separate tape or disc file. If you don't have the disc
>file, I found it inconvenient to have to read one tape before you can
>read the first, Esp. if it is a RELOAD or INSTALL. (It must be a look
>and feel issue, otherwise I think Orbit would have put theirs at the
>beginning too.)
Backup+ puts the directory at the end of the volume set such that it can
consolidate dynamic information in one place. Since we've always done
online backups where the sync point is at the end of the backup, we
can't commit the directory to the volumeset until we've finished the
online portion of the backup, hence, the directory is at the end. You
will now see cases with TurboStore (TS) as well where it must process
information from the end of the last tape when using sync at the end.
When using parallel backup and parallel restore (multiple devices),
you'll find that things operate more efficiently with the directory at
the end because we can determine exactly which tape blocks on which
tapes need to be restored. This is especially true when doing an online
backup such that a given block in a file is only restored one time and
one time only. Again, this applies to sync at the end which RR doesn't
do. In TurboStore's case, a block may be restored multiple times. If you
have a lot of online activity, this will be less efficient than the way
Backup+ does it, and that is primarily due to the fact that we can make
certain determinations when the directory is at the end than when it is
at the beginning.
>In RR you get a redo stack.
Backup+ includes a redo stack, TS doesn't.
>You can append to the same tape.
Backup+ also does appended backup to tape, and especially to DLT. TS
doesn't.
>A one-way version restorable with traditional RESTORE is at the
>beginning of the tape, so you can restore a RR backup to another machine
>that doesn't have RR.
Backup+ also behaves the same way.
>There is a some sort of algorithm built into the tape (could be hashing
>or markers) that restores a file quickly. I think the traditional
>restore sequentially reads through the entire tape before you get the
>file you're looking for. In other words, file zzz.zzz.zzz would be
>near the end of a store made using store @[log in to unmask]@. (This could be a long
>time on a DAT.)
Actually, I think all three products now make use of the Fast Search
capability of DDS. In addition, Backup+ makes use of the Fast Search
capability of DLT. This is more efficient on Backup+ with the directory
at the end (see above) because we know exactly at which block on which
volume the file begins.
>RR interleaves during store, configurable from 1 to 8 files at a time.
Backup+ and TS also interleave. Backup+ is configurable in a different
fashion. Files can be backed up file by file (e.g. all the blocks of a
file are processed together) or at the highest optimization level, the
extents of the files in the fileset are grouped by disk and a single
pass is made across each disk to back it up (effectively a track by
track backup).
>The high compression module is extra, 4:1 ratio.
Backup+ includes high compression in the standard version.
>Stores to a disc file if you want. Even partially, so that when all
>tapes are full, the rest can go to a disc file until the next new tape
>is loaded.
Backup+ does the same thing. TS doesn't.
>You can select using "MPEX style" file sets i.e. using MODDATE, CREDATE
>and ACCDATE.
Backup+ also allows the ability to select using dates as well as file
types (e.g. select type=image or type=ksam).
>This has become a plug so I'll guess I'll quit now.
Me too!
<plug mode off>
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