If you want to write in DDS-3 format on a DDS-3 drive, you MUST use 125 meter
tapes. If you want to write in DDS-2 format on a DDS-2 drive, you MUST use 120
meter tapes.
The DDS-3 drives are able to read DDS-2 and DDS format. The reverse is not
true.
My documentation says that with a DDS-2 drive, with 120 meter tapes, you can
get 512 KB/s to 1 MB/s in transfer rate. You get the same with a DDS-3 drive
and 120 meter tapes. If you use 125 meter tapes in your DDS-3, my
documentation shows a transfer rate between 1 MB/s and 2MB/s, depending on the
compression.
Also the capacity on DDS-2 tapes is 4-8GB (DDS-2) depending on compression,
versus 12/24GB on 125 meter tapes (DDS-3).
If you use 90 or 60 meter tapes, you are using DDS format which on a 90 meter
tape will store 2-4GB.
To set the compression, use DEVCTRL.MPEXL.TELESUP.
Kind regards,
Denys. . .
Denys Beauchemin
HICOMP
(800) 323-8863 (281) 288-7438 Fax: (281) 355-6879
denys at hicomp.com www.hicomp.com
-----Original Message-----
From: Connie Sellitto [SMTP:[log in to unmask]]
Sent: Monday, 15 November, 1999 9:05 AM
To: [log in to unmask]
Subject: DDS3 - compression
Hello Listers,
I sent out the following directly to Neil - no response to date - can any
of you help? Thank you!
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>>Hello Neil,
Hoping you can help... I searched HP3000 List archives for 'DDS3', and
found your postings regarding your experiences with a DDS3 drive. I'm
running a 937RX with 9.6 Gb disk, about 4.5 used, under MPE/iX 5.5. We
just purchased a used DDS3 to replace our DDS2 because we were told it
would reduce backup time. According to the HP reseller, no config changes
were needed, just power down the system, install the DDS3 drive, bring the
system up, and the system would recognize the new drive.
Well, the backup did work, but it didn't take any less time (about 50
minutes).
I noticed you used a 125 m tape - I have only 120 m DDS2, Will they work?
Also, how do I configure the drive for compression? SYSGEN ld on ldev 8 has:
ID: HPC1533A
MPETYPE: 4 MEPSUBTYPE: 7
CLASS: TAPE DAT
What do I have to do to use this drive as intended?
tia for your help,
Connie Sellitto
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