... [snipped for brevity] ... > > > Not to hijack this thread, but has anybody here tested the behavior > > of > > PG on a file system with OS-level caching disabled via forcedirectio > > or > > by using an inherently non-caching file system such as ocfs2? > > > > > > I've been thinking about trying this setup to avoid double-caching > > now > > that the 8.x series scales shared buffers better, but I figured I'd > > ask > > first if anybody here had experience with similar configurations. > > > > > > -- Mark > > > Rather than repeat everything that was said just last week, I'll point > out that we just had a pretty decent discusson on this last week that > I started, so check the archives. In summary though, if you have a > high io transaction load with a db where the average size of your > "working set" of data doesn't fit in memory with room to spare, then > direct io can be a huge plus, otherwise you probably won't see much of > a difference. I have yet to hear of anybody actually seeing any > degradation in the db performance from it. In addition, while it > doesn't bother me, I'd watch the top posting as some people get pretty > religious about (I moved your comments down). I saw the thread, but my understanding from reading through it was that you never fully tracked down the cause of the factor of 10 write volume mismatch, so I pretty much wrote it off as a data point for forcedirectio because of the unknowns. Did you ever figure out the cause of that? -- Mark Lewis
