[CLUE-Tech] tape backups

[Mike Staver]

Yeah, I'm actually used to Veritas Backup Exec for windows, and I love
how it catalogs what is on a tape, and the tapes are given an
identifiying name, so when you do an inventory, you know what's on it. 
BTW, Veritas does make a version for linux now, but I'm sure it requires
a GUI, which doesn't work for me.

Jim Ockers wrote:
> 
> > Wow, 5-6 hours?  I didn't realize tape was that slow.  I knew it was
> > slow, but not that slow!  I'll try it again with the verbose option
> > then, thanks.
> 
> Well you bring up an interesting point, which is worthy of discussion
> on this list.
> 
> I have used a couple of dozen SCSI tape drives, including some really
> fast ones (20MB/sec transfer rate to the tape), over the years.  I have
> found that commercial backup programs like Veritas and others do some
> real optimizations to the bytestream they feed to the tape drive,
> to avoid the "shoeshining" on the drive caused by insufficient buffering.
> 
> On the other hand, tar just writes blocks of data, and it is up to
> the drive to get them written to the tape.  There is no optimization
> that's done, and in fact it's quite slow.  I think on my 20MB/sec
> drive I got 1 MB/s or so using tar, IIRC.  There is plenty of shoe-
> shining on the drive because nobody is optimizing it.
> 
> Does anyone have any ideas how tar can be used but still achieve native
> drive speeds on the backup subsystem?  I've seen various schemes for
> buffering the tar input and output using dd (through the system RAM)
> but I've tried that and was underwhelmed by the speed increase.
> 
> Part of the optimization on commercial backup programs is that they
> stream several backups to the tape at the same time.  This means
> that the software has to keep a catalog of what's on the tape and
> where it is - otherwise it can be problematic to restore.
> 
> I like the simplicity of tar but the speed is atrocious.  It is
> completely unsuitable for any kind of short backup window, unless you
> just don't have much data.
> 
> Ideas, anyone?
> 
> --
> Jim Ockers (ockers at ockers.net)
> Contact info: please see http://www.ockers.net/
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-- 
                                 -Mike Staver
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