
5-16 IBM Informix OnLine Database Server Administrator’s Guide
How Is Tuning Done?
How Is Tuning Done?
If the value of Pages/IO is 75 percent or more of Bufsize, each write to the
diskis, on average, deferreduntilthe buffer is almostfull.(Since the valueof
Pages/IO is an average, some writes might be closer to 100 percent of the
buffer. The logging status affects this value; see the preceding paragraph.)
Inthiscase,you can try to furtherimprovebufferefficiencybyincreasingthe
size of the buffer to accommodate more data before each write.
If the valueof Pages/IO is less than75 percentof Bufsize, writesto thedisk
occur,onaverage,long beforethebufferisfully used.Inthiscase,youcantry
to improve buffer efficiency by decreasing the size of the buffer to more
closely approximate the size of Pages/IO. Decreasing the size of the buffer
frees shared-memory space for other uses.
Refertopage 3-93forfurtherinformationabouthowtochangethesizeofthe
logical log or physical log buffer.
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