The DAT40 is at the limit of what an SE-SCSI HBA can generate, which is why
the DAT72 is no faster. The DAT40 is able to run at less than its rated
speed without falling out of streaming mode. I think it's a combination of
the size of the buffer and its ability to adjust.
I wonder, Gilles, how much are you able to store on a cartridge? Do you
approach 40GB?
Denys
-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]] On Behalf
Of Gilles Schipper
Sent: Thursday, September 27, 2007 10:24 AM
To: [log in to unmask]
Subject: Re: [HP3000-L] dat40
At 08:46 PM 2007-09-26, Hawkins, Jim (HP, MPE/iX Lab) wrote:
>(top post warning).
>
>Of Denys two suggestions the 50-68 cable to an
>SE-SCSI HBA is more likely to provide a basic
>connection. The HVD/LVD converter would not
>work on k-Class as there are actually some
>driver restrictions in the NIO F/W SCSI HBA
>driver that prevent one from configuring a DDS
>as connected to a A28696A HBA bus (at least as far back as 6.5).
>
The 50-68 cable would be the one if connecting
directly to the se-scsi port of the k-class mfio card.
If daisy-chaining via other se-scsi devices, the
cable may need to change accordingly to match the connection points.
>At the same time "connect ability" does not mean
>"advisability" and never "supportability".
>
>o We didn't test the DAT40 on S900/NIO systems
>because its peak I/O bandwidth (6.0 MB/sec
>Asynchronous) was projected to exceed the
>capabilities of the SE-SCSI HBA (technically 5.0
>Megabytes/sec but really closer to 4
>MB/S). Historically it is not a good idea to
>run tapes at slower than rated speed as it
>causes the tape to drop from streaming mode into
>start/stop mode and excessive wear and/or bad
>performance result. Many tape drives do
>implement variable speed streaming but it wasn't clear that the DAT40 was
one.
>
>o We never certified any LVD-SCSI interface
>peripherals on the NIO-SE-SCSI HBA. Though all
>Wide LVD devices are technically supposed to be
>able to RUN (READ/WRITE/REWIND) narrow & SE-SCSI
>it is never advisable depend upon manufacturer
>actually testing all device functionality in
>such a hobbled mode. Additionally newer devices
>may spit out "SCSI Standard" information that very old drivers will choke
on.
>
>o No idea what the PDC would do if you tried to
>boot from a CSLT on this device. . .
>
>This means that DAT40 is NOT supported by HP via
>SE-SCSI on S900 NIO systems (9x8,9x9,99x &
>earlier). Works fine and is supported by HP on A/N-Class.
>
>So, I'd advise you only use this kind of set-up
>to write data you are willing to lose ;-)!, OR
>at least make sure your back-up application
>vendor is willing to support you. YMMV. . .
Supported or not, it WORKS.
In fact, it more than works.
Not only can you boot from it, on a k-class it
performs significantly faster than a dds3 drive.
On an N-class, a full backup using STORE can
complete in one-third the time when compared to a dds3.
The bottom line is that the dat40 shines on
virtually all HP3K models, with performance
advantage over the dds3 increasing with increasing HP3K cpu speed.
Also, the dat72 (aka dds5) also works very well
with the 3k - although its performance is almost equal to the dat40.
>Jim Hawkins
>MPE/iX I/O Architect
>
>
>-----Original Message-----
>From: HP-3000 Systems Discussion
>[mailto:[log in to unmask]] On Behalf Of Denys Beauchemin
>Sent: Wednesday, September 26, 2007 12:32 PM
>To: [log in to unmask]
>Subject: Re: [HP3000-L] dat40
>
>Hello Christian, long time.
>
>I believe the DAT40 is an LVD device which would require you to connect it
>via a 68 to 50 pin cable with high-bit termination or to a 68 bit SCSI port
>on the 3000 using a converter to allow you to switch from HVD (HP3000) to
>LVD or SE (DAT40).
>
>Denys
>
>-----Original Message-----
>From: HP-3000 Systems Discussion [mailto:[log in to unmask]] On Behalf
>Of Christian Scott
>Sent: Wednesday, September 26, 2007 1:20 PM
>To: [log in to unmask]
>Subject: [HP3000-L] dat40
>Importance: High
>
>Hi,
>
>
>
>I need to find out if I can connect a dat40 on a hpe3000 k-class server, if
>so what are the step involve.
>
>
>
>Thanks,
>
>
>
>Christian Scott
>VP - Development & CTO
>201 Rue Laurier Est
>Suite 630
>Montréal, Québec
>H2T 3E6
>
>Tel: 514-273-0008 x118
>Fax: 514-273-0199
>Email: <mailto:[log in to unmask]> [log in to unmask]
>
>Web: <http://www.softvoyage.com/> www.softvoyage.com
>
>
>
>
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>
>
>--
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----------------------------------------------------------------------------
---------------------
Gilles Schipper
GSA Inc.
HP System Administration Specialists
300 John Street, Box 87651 Thornhill, ON Canada L3T 7R4
Voice: 905.889.3000 Fax: 905.889.3001
email: [log in to unmask] web: http://www.gsainc.com
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