Re: Oracle SGA and HPUX Buffer Cache

G.K.Subramanian (gks_at_mailbag.com) wrote:
: Hi,
:
: I have been getting different feedback on the above topic.
:
: Issues : Should we use HP UX Buffer cache on the system
: running ORACLE applications.
:
: Understand the HP Buffer cache is not likely to improve
: I/O for Oracle data blocks, since SGA does the same function.
: I was also told by ORACLE, that in some cases the HP Buffer
: cache may even degrade performance for ORACLE in some cases.
:
: My understanding is that HP Unix uses buffer cache to
: improve I/O performance, independent of what applications
: you run. Although SGA may do a similiar function, it does
: hand it over to the UNIX at some point of time.
:
:
: I am currently using 30% of memory (512M) for buffer cache.
: Does anyone know the optimum value, or say that we don't
: need to use the Buffer cache.
:
:
: Our configuration.
: ==================
:
: HP K210 , 512MB RAM / 40GB disk
: HP UX 10.01,
: Oracle 7.x
:

The usual HP recommendation on this at 10.x are 20% or 200 MB whichever is less. The default settinge for kernel parameters dbc_min and dbc_max are 5 and 50 respectively, though.

dave

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David-Michael Lincke
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