Monday, November 3, 2008

Deprecated and new Oracle related parameters on 11iv3

These parameters are now obsoleted/deprecated @ 11iv3:


the filecache ones are new starting with that release

dbc_* have been obsoleted by filecache.

nfile is still there, but shouldn't be used (deprecated).

msg* and maxswapchunks are gone (maxswapchunks has been gone since 11.22...

But Oracle's recommendations are based on outdated information and can be ignored in this case.

dbc_min_pct and dbc_max_pct has been replaced with filecache_min and filecache_max.
These are compatible with dbc_min and dbc_max tunables and maintain the same semantics.
So hp recommands to keep the values same, that is,
dbc_max_pct => filecache_max
dbc_min_pct => filecache_min


dbc_max_pct => filecache_max

dbc_min_pct => filecache_min

dbc_max_pct, dbc_min_pct, bufcache_max_pct, bufpages, nbuf — OBSOLETED kernel tunable parameter.
This parameter indicates how much of physical memory the I/O buffer cache can expand up to
(the buffer cache is used to cache commonly used disk pages so that future I/O requests for
those pages is substantially faster). dbc_max_pct represents the maximum size, and should
memory pressure occur, the buffer cache will decrease in size to a minimum of dbc_min_pct.
The default value for dbc_max_pct is 50 (i.e., half of physical memory). For workloads where
the HP-UX system is acting as only the Application Server tier, there usually is not substantial
disk activity. Consequently, you can reduce this parameter to a much lower value of, typically, 10%.
On HP-UX 11i v3 dbc_max_pct, dbc_min_pct, bufcache_max_pct, bufpages, and nbuf kernel parameters are
obsoleted and removed. Use the file cache tunables filecache_max and filecache_min (see man filecache_max(5)
for more details).
These tunables control the amount of physical memory that can be used for caching file data
during file system I/O operations. The default value for filecache_max is 50. The value of the minimum limit,
filecache_min, can be lowered to allow a larger percentage of memory to be used for purposes other than
file system I/O caching, depending on competing requests. By lowering the value of filecache_max, to 10%,
a larger amount of memory is available for other purposes, without competing with file I/O requests.

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