On Thu, Sep 4, 2008 at 2:01 PM, Ulrich <ulrich.mierendorff@xxxxxxx> wrote: > Scott Marlowe wrote: >> >> On Thu, Sep 4, 2008 at 1:39 PM, Ulrich <ulrich.mierendorff@xxxxxxx> wrote: >> >>>> >>>> I wouldn't set shared_buffers that high >>>> just because things like vacuum and sorts need memory too >>>> >>> >>> Okay, I understand that vacuum uses memory, but I thought sorts are done >>> in >>> work_mem? I am only sorting the result of one query which will never >>> return >>> more than 500 rows. >>> >> >> You can probably play with larger shared memory, but I'm betting that >> the fact that you're running under a VM is gonna weigh eveything down >> a great deal, to the point that you're tuning is going to have minimal >> effect. >> > > Hmm... Why do you think so? Is there a reason for it or do other people have > problems with virtual servers and databases? > I have reserved cpu power and reserved ram (okay, not much, but it is > reserved ;-) ), the only thing I dont have is reserved file-cache. Well, Databases tend to be IO bound, and VMs don't tend to focus on IO performance as much as CPU/Memory performance. Also, things like shared memory likely don't get as much attention in a VM either. Just guessing, I haven't tested a lot of VMs.
