Lars Feistner <feistner@xxxxxxxxxxxxxxxxx> wrote: > On 03/30/2011 06:54 PM, Kevin Grittner wrote: >> If you haven't already done so, you should probably turn on >> checkpoint logging to see if this corresponds to checkpoint >> activity. If it does, you can try cranking up how aggressive >> your background writer is, and perhaps limiting your >> shared_buffers to something around the size of your RAID >> controller's BBU cache. (I hope you have a RAID controller with >> BBU cache configured for write-back, anyway.) > i am sorry to disappoint you here. As I said in my first E-Mail we > don't have much traffic and the database fits easily into memory. > The traffic might increase, at least it was increasing the last 12 > months. The database will always fit into memory. > No, we don't have a raid and thus we don't have a bbu. Actually > we started off with a big SAN that our data centre offered. But > sometimes this SAN was a bit slow and when we first encountered > the very long updates i thought there was a connection between the > long running updates and the slowliness of the SAN, so i started > to use the local disk (we are talking about one disk not disks) > for the database. I am still seeing the long running inserts and > updates. I am still following the auto vacuum trail, it does still > not run frequently enough. Thanks a lot for the replies so far. I > will keep you guys informed about my next steps and the results. Nothing there makes a write glut on checkpoint less likely to be the cause. Without a BBU write-back cache it is actually *more* likely, and having enough RAM to hold the whole database makes it *more* likely. If you haven't placed your pg_xlog directory on a separate file system, it is also more likely. Turning on logging of checkpoint activity and checking whether that correlates with your problem times is strongly indicated. -Kevin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
