From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Miguel_Gonz=E1lez_Casta=F1os?= Subject: Load Balancer, fail tolerance and replication in PostgreSQL Date: Mon, 12 Apr 2004 14:35:13 +0200 Sender: linux-admin-owner@vger.kernel.org Message-ID: <407A8D01.5010901@tid.es> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: List-Id: Content-Type: text/plain; charset="iso-8859-1"; format="flowed" To: linux-admin@vger.kernel.org Dear all, We have a web application served by Apache with Tomcat behind for the= =20 JSPs. The database backend is PostgreSQL. I have been asked to do some research about how to achieve fail tolerance and load balancing in our=20 application. After searching a little bit this is my first impression: - There are integrated software for high availability using PostgreSQ= L=20 (i.e.: eRserver) but have commercial licences (you have to pay a lot fo= r=20 it). - There are some efforts for developing GPL application to achieve=20 replication, or load balancing or even clustering. My impression is tha= t=20 they are in a earlier stage, but some of them look promising. Anyway I=20 am not very sure if any of them will suit into my setup (like pgcluster= =20 or dbmirror). What I have thought that in my setup maybe I just need to do=20 clustering with servers with the same setup: Apache/Tomcat. Then, just= =20 do some sort of replication between the PostgreSQL databases that every= =20 node of the cluster should have (i dont know which is the best GPL=20 replication software). Even I thought that maybe I could use some sort=20 of dns round- robin approach for load balancing for Apache. Anyway as you can see I=B4m pretty lost and I need some guidance to p= ut=20 me in the right direction... Sorry for my English Many thanks in advance Miguel Se que en Bulma sois mas forofos de MySQL que de PostgreSQL por vuestras experiencias con la web de bulma, pero tengo que hacer un estudio para usar PostgreSQL en un entorno donde se necesita balanceo d= e carga y tolerancia a fallos. Realmente lo que tenemos es una aplicacion web, con Apache y Tomcat como servidores de JSPs cuya base de datos es PostgreSQL, digo esto porque he pensado que tal vez lo de buscar un sistema de alta disponibilidad para PostgreSQL no sea necesario para este sistema, y simplemente lo que podria hacerse seria un cluster con Apache, o inclus= o utilizar un algoritmo round-robin que vaya pasando las solicitudes a lo= s distintos servidores y un sistema de mirroring entre los distintos servidores PostgreSQL. He estado mirando en la p=E1gina web de PostgreSQL y navegando un poco,= y veo que hay alternativas que ofrecen alta disponibilidad (tolerancia a fallos, balanceo y replicacion), pero de pago. Como os digo se me ocurre a priori este enfoque que os digo, ya que realmente solo hay una base de datos que mantener sincronizada (creo qu= e esto se puede hacer con dbmirror aunque no se si es solo a nivel de tablas o de bases de datos). Tambien he visto una herramienta llamada pgcluster. La verdad estoy un poco perdido, alguien me puede echar un cable? Un saludo Miguel - To unsubscribe from this list: send the line "unsubscribe linux-admin" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html