How many Siemens printers can be attached to an RS/6000
ITEM: RTA000093607
Q:
ABSTRACT: How many PSF/AIX printers can be attached to an RS/6000?
SEARCH ARG: psf/6000 performance
TOPIC THREAD: PRINT
AFP
PSF6000
..
A direct-mail customer has 15 Siemens printers (nine 2240's and six
2140's) attached to a VSE system printing line mode applications.
If they would stay with the line mode applications (approx 5K bytes
page), how many of these printers can I attach to an RS/6000?
At this point, all I need is a ball park figure. Thanks for the help.
A:
| Updated October 1996.
The first thing to note is that unlike the newer IBM 3900s that can
attach to a TCP/IP network (either token-ring or Ethernet), the OEM
printers will have to attach through the S/370 Channel Emulator/A
adapter. You can only attach one printer per S/370 Channel Emulator/A
adapter. The *maximum* number of S/370 Channel Emulator/A adapters you
can have in an RS/6000 is four. Not all RS/6000s support this adapter
| (feature code 2759). To receive the driver needed to support this
| adapter, please order current maintenance for PSF for AIX, and read
| and follow the instructions that ship with the PTF. The practical
number of adapters is limited (1) by the number of microchannel slots
available in the RS/6000 and (2) by performance considerations. Note
that you may need one or more microchannel slots for other adapters,
such as graphics adapters, so keep that in mind when allocating slots.
Although we have not done extensive performance testing of multiple
printers off of multiple S/370 Channel Emulator/A adapters, it does
appear that there is some overhead associated with multiple cards in
a single RS/6000. In our test of two channel printers, two cards, one
RS/6000, the printer throughput degraded about 5% when compared to
two channel printers, two cards, two RS/6000s.
Let me take you through the basic calculations based on the information
in the PSF/6000 Performance flash (IBM Confidential; available by
request from the PENNCONF disk as per the instructions in the PSF6PERF
PACKAGE on the PRINTERS disk). Then you should be able to use this
as a basis for further extrapolation.
Since you said the input would be line data, you look at Table 3 on
page 13 of the Performance Flash. The closest we have to a 5K page
is LTX1U08K. Let's use the data for the Model 370. Please reference
the methodology we describe beginning on page 32 of the flash.
The general equation would be:
IPM * {(CPUsecs/page) / (60secs/min)} * 100 = approx. CPU util.
where IPM is the total number of impressions per minute you want to
drive and CPUsecs/page is the CPU seconds per page from the table.
On a Model 370 for LTX1U08K, the number of Model 370 CPU seconds per
page (far right columns) for transform and print is .025 + .018 = .043.
In this case IPM is the unknown, so we'll assume a target CPU
utilization of 65% (so there's room for AIX spooling and overhead, and
the unknown overhead of multiple adapters). The formula becomes:
IPM = 65 / (.043 / 60 * 100)
That comes out to 907 IPM for a Model 370. If you want to be
conservative given the unknowns, you could recalculate for a 60% load
for an estimated IPM of 837. You can then figure out how many printers
you could drive from Model 370 using this information and the number
of available slots.
The performance flash methodology also provides some guidance on how
to extrapolate this estimate to other RS/6000 Models based on the
SPECint92 and SPECfp92 benchmarks (which are available in the RSFACT
PACKAGE on AIXTOOLS). The 5xx series of RS/6000 have more slots than
do the 3xx. Note that a 570 is less powerful (according to the
benchmarks) than a 370.
I hope this helps.
S e a r c h - k e y w o r d s:
AIX PSF/6000 PSF FOR AIX PERFORMANCE SIZING RS/6000 SIZE MODEL CHANNEL
oce siemens 2759 microchannel s/370 adapter emulator attach psf/aix
WWQA: ITEM: RTA000093607 ITEM: RTA000093607
Dated: 10/1998 Category: XPSF6000
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