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08877 - Parallel Backup with 3 Tapes
Addresses (Business Address Services) Fill RESBD Structure from EBP Component StructureThis documentation is copyright by SAP AG.
Parallel Backup with 3 Tapes
Franz,I understand that you wonder why a third tape does not reduce your
backup time, what you are up against is what we in danish would call
a bottleneck.
When you look at the route from "data on disk" to "backup on tape"
there are a number of elements that has influence on performance and
throughput
The first thing that comes to mind is your iSeries processor. An
iSeries or AS/400 server can save from 17 Megabyte/second (7xx) to
40 MByte/second (8xx). This "low" number is no problem on a 7xx
server because this number is in sync with systembus (25 MB/sec) and
tape controller (SPD 6533/6501 17 MByte/sec or PCI 2729 13 MB/sec).
An 8xx server has a new systembus (700 MByte/Sec)so on such a server
systembus is no bottleneck. Tape controller in an 8xx server can
handle 38 MByte/second for a SCSI 2749 controller and 100 MByte/Sec
for a fibrechannel tape controller (2765). Last but not least, the
tape drive it self has a devicerate that can be a bottleneck. A 3590
E SCSI can save 34 MByte/sec and a 3590 E Fibre can save 43 MByte/sec.
Having a 8xx server with three 3590 tape drives doing a parallel save
will allow you to save about 100 Megabyte/second with scsi and 120
Megabyte/second with fibre but looking at above bottlenecks you will
realize that the processor can not deliver this huge volume of data!!
So I agree with Volker and Doreen, the solution for you is a HA
application. Ask the HA vendor to demo their HA application with
remote journal as transport mechanism instead of the old
fashioned programme to programme approach.
I disagree totally with Peri, do not implement a Shark SAN.
If you do anyway, please make shure it is sized propperly and listen
to your iSeries Specialists, not the storage sales people, and
implement a two-shark PPRC solution with long distance between the
two sharks. A SAN solution has the disadvantage that you cannot
backup the copy, you still have to figure out a way to do a
tapebackup from time to time!
Stay tuned for the upcomming iSeries announcement, there are good
news on I/O performance and I think that there is a tape announcement
from the LTO manufacturers here in Q1 of 2003 as well.
You can find further information in the iSeries book "iSeries
Performance Capabilities Reference"
Med venlig hilsen/Regards
Mølgaard Data A/S
Jørgen Johansen
SAP Certified Technical Consultant AS/400
IBM Certified Solutions Expert iSeries Technology
Phone: +45 64 400 610 Fax: +45 64 400 612 Mobile: +45 20 220 610
http://www.mgd.dk
Remember... when the sun goes down, iSeries stays up
--- In DoNotReply@consolut.eu, "Lehnardt, Franz"
<franz.lehnardtZu...> wrote:
> Hi group,
>
> last weekend we attached a third 3590 to our PRD server to reduce
the
> runtime for backup of our PRD system. We hoped to save at least 15-
20%
> runtime, but nothing changed at all - the backup still runs as long
as with
> 2 units.
>
> So is there anyone out there already running backups with more than
2 tape
> units and if so, what are your experiences?
>
> Thanks for any advise.
>
> Mit freundlichen Grüßen / Best regards,
>
> Franz Lehnardt
> AS/400 Administration
> Unielektro Fachgrosshandel GmbH & Co. KG
> Eschborn, Germany
> Tel. +49 (0) 6196 477-360
> mailto:franz.lehnardtZu...
>
>
> [Non-text portions of this message have been removed]
Durban Tours - Südafrika Safari
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