Re: AIX Fibre Attached Storage (SAN) to XP1024 and XP12K storage throughput problems

CernerJoe wrote:
> Yes, they are on separate busses and all firmware and microcode is up
> to date.
>
> Given the nature that this spans versions of aix, companies, adapters,
> arrays, etc... I don't believe you will find a common point outside
> the AIX I/O subsystem currently in use.
Our system has over 200MBytes/s ( AIX 5.1 on an EMC fabric and a CX600
)

>>From the book:
Maximum Number of Commands to Queue to the Adapter:
Use this option to adapt to various memory/system conditions. The
default is 200, but you can conserve memory at the expense of
performance by reducing this number to as low as 20. If you have
sufficient memory, the maximum is 1024 for a Gigabit Fibre Channel PCI
Adapter (Type 4-S). The maximum is 2048 for a 2 Gigabit Fibre Channel
Adapter for 64-bit PCI Bus (Type 4-W).
If the SCSI target device is connected to the host through a SAN Data
Gateway (SDG), this parameter cannot exceed the SDG limit of 240 (SAN
Data Gateway is a SCSI-to-Fibre Channel bridge).

Maximum Transfer Size: The default is 256 kilobytes, which is the
largest single transfer size. For tape, transfers of 2 megabytes or
more are possible. The range is 256 kilobytes to 16 megabytes.

So:
1) Do not use any non IBM Multipath and whatsoever driver
Redo your test
The best would be to test ONE fc hba only with native device driver.

2) Configure the Adapter to at least 1024 Max. No of Commands to Que...
Redo your ..

3) Test JFS and JFS2 Filesystem
Redo ...

4) Do tests bypassing the LVM manager ( raw access to the device, no
buffering or DIO mount option for JFS and i think CIO for JFS2 )

5) Test against a single physical disk on the XP - At least on EMC you
can assign a disk to a host - so bypassing any Blocksize,transfer size
regarding raid configuration.

hth
Hajo

.

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