Interesting. You should know that if you are using 125Meter tapes, you are
actually using the DAT40 as a DDSIII device, not a DAT40 (same if you use
the 125M tapes in a DAT72.)
The reason for your increased throughput is due to the tape drive turning
the tape faster, not because it is writing as a DAT40. The drive would
operate faster with a 150M tape.
I would love to read about Neil's experiences. (He's from South Africa, not
New Zealand, btw.) One should be able to store a lot of data in such an
autoloader.
Thanks for the great info.
Denys
-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]] On Behalf
Of Gilles Schipper
Sent: Thursday, September 27, 2007 9:56 PM
To: [log in to unmask]
Subject: Re: [HP3000-L] dat40
The following statistics are associated with a
HP3000/N4000 full backup to a dat40 tape drive utilizing a dds3 tape.
(dat40-native 150-meter tapes are not used
because of existing high available inventory of
125-meter tapes and no perceived benefit of use
of higher-capacity tapes, since full backup fits entirely on a single tape).
Total backup file data on media: approx. 33gb
Total compressed data on media: approx. 10gb
So, given the same compression ration of better
than 3 to 1, in this example we could assume an
additional 20% of file data before we would need
to purchase 150-meter tapes or suffer a second media for the backup.
A dds3 (aka dat24) tape has a native capacity of
12gb; dds4 (aka dat40), 20gb; dds5 (aka dat72), 36gb.
I believe Neil Harvey in New Zealand has been
utilizing a dat40 autoloader which satisfies a
hands-free backup requirement for multi-media backups.
If you're still lurking, Neil, please correct me if I'm wrong.
A very good reference to the existing and
emerging DDS/DAT technology is available at www.datmgm.com.
At 09:17 PM 2007-09-27, Denys Beauchemin wrote:
>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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> >
> >
> >
> >--
> >No virus found in this incoming message.
> >Checked by AVG Free Edition.
> >Version: 7.5.488 / Virus Database:
> >269.13.32/1032 - Release Date: 2007-09-26 8:20 PM
>
>---------------------------------------------------------------------------
-
>---------------------
>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
>---------------------------------------------------------------------------
-
>---------------------
>
>* To join/leave the list, search archives, change list settings, *
>* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
>
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>* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
>
>
>
>--
>No virus found in this incoming message.
>Checked by AVG Free Edition.
>Version: 7.5.488 / Virus Database:
>269.13.32/1032 - Release Date: 2007-09-26 8:20 PM
----------------------------------------------------------------------------
---------------------
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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* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *
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