DLTs are probably much more reliable.
I don't have experience with DDS-4s, which are supposed
to be much better than DDS-3s.
On older HP systems, you need a dedicated SCSI channel per drive
for DLTs.
New DLT drives are out that are slower, but much cheaper than
the DLT8000s, but use the same tape and 40gb uncompressed capacity.
(they write an incompatible format.)
If you have lots of highly compressable data bases,
the compression ratio may be more like 3-1 or even 4-1
if you data bases aren't real full. Thus you should
be able to fit a 30gb data base easily on a 12GB native capacity
DDS-3 tape, and certainly on a DDS-4 20GB native.
I didn't think HP supported the DDS-4 yet on HP3000s.
I can't get my systems to store anywhere near the DLT7000
maximum rate. I get about 4, 5 and 6mb a second on my
HP939, HP989 and HP979-200 respectively, with 1,2 and 3 SCSI
controllers for the discs, respectively. If I don't do the
interleave option on store, the speed goes down.
If wall clock time is not a major factor, a DDS-4 tape should hold
you for a while.
-----Original Message-----
From: Tom Brandt [mailto:[log in to unmask]]
Sent: Wednesday, April 04, 2001 4:08 PM
To: [log in to unmask]
Subject: [HP3000-L] OT: Lan backup - DDS vs. DLT
I need to upgrade my Lan backup facility. Currently, I backup roughly 14GB,
this should grow to around 30GB by the end of the year.
I am looking at HP DDS and DLT drives in the Global catalog.
The HP DDS-4 drive (external) costs $1400, capacity is 40GB, transfer rate
is said to be 10.8GB/hour.
The HP DLT-4 drive (external) costs $2100, capacity is 40GB, transfer rate
is said to be 10.8GB/hour.
DDS-4 tapes cost $40/ea in single quantities, DLT IV data cartridges cost
$90/ea in single quantities.
The cost differences between DDS and DLT are pretty significant, so I am
wondering if there is some advantage to choosing DLT which would justify
the cost increase. Anyone out there with experience in this area (like
Denys?)
--------------------------------
Tom Brandt
Northtech Systems, Inc.
313 N. 1st Street
Ann Arbor, MI 48103
http://www.northtech.com/
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