synchronous IO and dbc_max_pct

[Nappyb6]

we are using synchronous IO in a vxfs file system under hpux11.11 (default setting).

i think that the system doesn't need a great amount of cache memory for the file system.

is that true ?
should i decrease this parameter to 1% (physical memory=16GB) ?

[Calandrello]

Friend
sync uses the command to synchronize again.

[Steve Steel]

Hi


What are you doing with the system

More important

see
http://h21007.www2.hp.com/dspp/files/unprotected/database/HP3KOracle.ppt#351,15,Slide 15

For a good example with oracle


steve Steel

[A. Clay Stephenson]

You really shouldn't confuse O_SYNC and/or D_SYNC with raw/io -- they are quite distinct. While open()'ing files with D_SYNC does reduce the demands on the buffer cache, the buffer cache is still used for all regular files that are open()'ed with the normal attributes. I would be very reluctant on any system with reasonable amount of memory to reduce the buffer cache below about 400MiB.