Tuning JFS2 Buffers for Improved I/O Performance
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JFS2 buffers often needs to be tuned for I/O intensive applications. The performance gains can be large. Last month I was involved in a stress benchmark where JFS2 tuning improved batch performance by a factor of three.
To determine if your AIX system needs JFS2 tuning, run the "vmstat -v" command several times over a period of 10-30 minutes during peak processing. If the number of "I/O's blocked with no fsbuf" increases with time, you need to increase JFS2 buffers.
Increasing JFS2 buffers is straightforward. Simply increase the j2_d
You may have noticed this method differs from how we tuned JFS2 in the past, In the past we would increase j2_n
ioo -h j2_d
My guidelines for initial settings when running I/O intensive applications are as follows:
1. Set j2_n
My reasoning is that j2_n
Finally, you should be aware that there are other options for tuning I/O (j2_