Thanks for the quick reply. I will look forward to release 1.5 or 1.6. Is there a (very rough) ETA on those releases?
Best regards, Ben On Fri, Jul 23, 2010 at 10:35 PM, Willy Tarreau <[email protected]> wrote: > Hello Ben, > > On Fri, Jul 23, 2010 at 03:21:03PM -0700, Ben wrote: >> Hello -- >> >> I've searched for this on the mailing list but I haven't found an >> answer, hope someone can help! >> >> I have a setup like >> >> 5 machines (m1,..,m5) >> 2 services (s1, s2) >> >> Each machine has one or both of the services, each instance of each >> service is identical. I want to present each service as a single >> entity, but I'd also like to limit the maximum number of connections >> to the machines. The obvious way to do it would be to set up two >> backends in the configuration, one which points to all the machines >> which have s1, the other to the machines with s2. But there will be >> some overlap in the machines, so the machines might get overloaded >> with connections (if I keep the maxconn parameter the same in each >> backend) or else be underutilized (if i split the connections between >> the backends, and only one service is being requested.) >> >> For concreteness suppose my setup is >> >> m1, m2, m3 have s1 >> m2, m3, m4, m5 have s2 >> (so m2,m3 have both services.) >> >> Is it possible to have server (with maxconn) shared between backends? > > No, this is something which is planned for version 1.6 but which *may* > finally get into 1.5 if it happens to be easier than initially thought. > Your example is interesting BTW, because your backends are heterogenous, > so it proves that the association must clearly be between individual > servers. > >> Or is there another way to accomplish my goal? > > Not really. When backends are similar, it's quite common that people > use a same backend for both services, assuming there's little or no > risk of losing one service without the other one. If yours are different, > then I would still suggest to have two backends with half of the maxconn > in each (or slightly higher if you know that both services are not really > saturated at the same time). While this can be perceived as having > underutilized servers, it's not true in practice, because the maxconn > you set indicates the limit the server cannot handle. It does not mean > the server cannot be full far below. For instance, I know some people > who set their apache to a very low maxconn of 30, because it's the level > they observe the best performance for their app. But the servers are > configured with MaxClients 256, so you can fully use them with any value > between 30 and 256. That means that one backend at 30 will be able to > saturate them, and two backends at 30 too, without risking stability. > > In fact, the only case where this is not really possible is with mongrel > which has a maxconn of 1 that you can't split ! > > Best regards, > Willy > >
