IBM AIX I/O Performance Tuning


 
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Operating Systems AIX IBM AIX I/O Performance Tuning
# 8  
Old 03-11-2019
To change max_xfer_size does one require to reboot AIX? I was reading this blog which mentions the command to run followed by a reboot, is there any way around the reboot?
# 9  
Old 03-11-2019
Hi - as you can see in your results the xdisk tool with 1 MB block size drove the V7000 up to 3.4 Gigabytes per second.
The reason I mentioned using 0x40000 for the hdisk max_transfer is because that is what the SDDPCM driver used by default and I have seen better V7000 performance with this value compared to the 0x80000 default that AIX MPIO uses.
You can leave the FC adapter at 0x100000 or you could change it to 0x200000. This tunable is independent of the hdisk one.

If you do reduce the hdisk max_transfer from 0x80000 to 0x40000 you can then compare the xdisk results now that you have already run it once.

Thanks
Dean

--- Post updated at 09:05 PM ---

Regarding your question of tuning max_xfer_size you can do it dynamically assuming your LUN's have multiple paths. (lspath to confirm)
Code:
rmdev -l fscsiX -R
chdev -l fcsX -a max_xfer_size=0x200000
cfgmgr

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