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A DLT 4000 is rated at 1.5 MB/s native (5.4 GB/h), 3 MB/s compressed
(10.8GB/h).  A DLT 7000 is rated at 5 MB/s native (18GB/h) and 10 MB/s
compressed (36GB/h).  You should not expect to be able to reach the full
compressed speed, but you might come fairly close, if your disk subsystem
can supply the data fast enough.

For higher backup speeds, use multiple DLT 7000, as it is unlikely HP will
in the near future, support faster devices such as IBM Magstars (9MB/s
native), StorageTek Redwoods (11MB/s) or Eagles (15 MB/s) on the HP 3000.

Kind regards,

Denys. . .

Denys Beauchemin
HICOMP America, Inc.
(800) 323-8863  (281) 288-7438         Fax: (281) 355-6879
denys at hicomp.com                             www.hicomp.com



-----Original Message-----
From:   Howard Hoxsie [SMTP:[log in to unmask]]
Sent:   Monday, 12 April, 1999 3:53 PM
To:     [log in to unmask]
Subject:        Re: DLT7000 vs DLT4000?

Is there a chance that the F/W SCSI channel is the bottleneck?  I seem to
remember that they are 20mb/sec and that the DLT7000 can go faster than
that
if it is on a High Speed SCSI channel.  Hope I'm not barking down the wrong
cable here.....

Can anyone confirm or deny?  I'm interested in checking out DLT7000's
myself, primarily for the high-volume backup capability of 70Gig
compressed.

Thanks,
Howard Hoxsie
> -----Original Message-----
> From: Carl McNamee [SMTP:[log in to unmask]]
> Sent: Monday, April 12, 1999 12:22 PM
> To:   [log in to unmask]
> Subject:      Re: DLT7000 vs DLT4000?
>
> We are using the INTER and MAXTAPEBUF options in Turbo Store.  We ditched
> Road Runner and that would be another LONG discussion.
>
> Denys had a good suggestion to see if the data we are working with may be
> causing a bottle neck on the disk i/o side. We are going to try a backup
> of
> the test data to $null and see how long it takes.
>
> Carl
>
>
> >Because the tape drives are not the limiting factor in your backup
speed.
> It's
> >probably time spent fetching data from disk and preparation for sending
> to
> >tape.  Are you interleaving files on tape?
>
> >Also, RoadRunner doesn't read a file which spans multiple drives in
> logical
> >sequence.  It is aware of which extents fall on which spindle and reads
> extents
> >on multiple drives concurrently as much as possible.  This also helps
> increase
> >the parallelism of disc reads during the backup.  I don't know whether
> >TurboStore also does that, but with the TurboStore default of no
> interleaving,
> >it's my understanding that the files are always stored in logical order
> on
> >tape...  hence the file has to be read one extent at a time in order.
>
> >If you use RoadRunner, which if I recall correctly you used to use
there,
> try
> >increasing the interleave to 8.  If you use TurboStore, then add the
> ;INTER=
> >option and run your test again.  I would be very interested in seeing
the
> >results.
> >--
> >Jeff Woods
> >[log in to unmask]  [PGP key available here via finger]