On 04/27/2011 11:33 PM, HSIEN-WEN CHU wrote:
> When database files are on a VxFS filesystem, performance can be
> significantly improved by setting the VX_CONCURRENT cache advisory on
> the file according to vxfs document,
>
That won't improve performance, and it's not safe either. VX_CONCURRENT
switches the filesystem to use direct I/O. That's usually slower for
PostgreSQL. And it introduces some requirements for both block
alignment and the application avoiding overlapping writes. PostgreSQL
doesn't do either, so I wouldn't expect it to be compatible with
VX_CONCURRENT.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us