Skip wrote:
I have heard that the FICON Express4 4-port adapters which operate at
4Gbps speeds become slower/degraded with each channel added to the
card. That if I fill the 4 ports I may be as slow as 1/4 the rated
speed. Has anyone else heard or read about this? Is it true?
I asked our local expert about this. Her response:
For FICON Express4, the speed of the Self-Timed Interconnect (STI) bus
(the path for communication between System z memory and I/O) was
increased from 1GB/sec to 2GB/sec to support the higher bandwidth that
each of the four channels are designed to generate when running at 4
Gigabit/s link speeds.
Measurements were done with all four FICON Express4 channels active on
the same card to determine the maximum MB/sec capability of the FICON
Express4 feature. Measurement results were compared to the FICON
Express2 feature which had a 1GB/sec STI bus and the previous generation
FICON Express feature which had 2 channels per feature connected to a
333MB/sec STI bus. For the FICON Express4 feature, a maximum of 1230
READ MB/sec, 1150 WRITE MB/sec and 1300 READ+WRITE MB/sec was measured
which represents up to 1.3 to 1.9 times more throughput than a FICON
Express2 feature and up to 4.4 to 6.9 times more throughput than the
previous generation FICON Express feature.
Please refer to the figure on page 7 of the technical paper System z9
I/O and FICON Express4 Channel Performance
which can be found at:
http://www-03.ibm.com/systems/z/connectivity/index.html
Performance information is on the 4th tab. The link to the referenced
technical paper can be found at the bottom of the page.
Connie K. Beuselinck
System z Hardware Product Planning
IBM Corporation
Poughkeepsie, NY U.S.A.
--
John Eells
z/OS Technical Marketing
IBM Poughkeepsie
[EMAIL PROTECTED]
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