Hi John, >>On Wed, Sep 2, 2009 at 2:52 PM, it-intuition <[email protected]> wrote: >> >>Hello, >> >>we are currently using lvs for balancing two webservers by using the wrr >>scheduler in combination with persistance. >>Now we want to modify our setup to use one primary webserver and a >>secondary webserver as a backup server. My idea was to set the weight of >>the primary webserver to 1000 and for the backup server to 0. >> >>These are the question that came up in my mind: >> >>1. How will this setup behave if the primary webserver is down? >> >>2. How will this setup behave if the primary webserver is up again? >> >>3. Does a weight of 0 mean, that no connection to the backup server can >>be made (if the primary webserver is down)? >> >>The last question may sound stupid, but I read that a weight of 0 is >>often used to silently take a server out of a pool. >>So I think a weight of 0 prevents clients to connect; which is not the >>effect I want for our setup. >> >>Any help or comments would be appreciated. >> >>Gerd >> >>
>I run 4 OpenLDAP servers in multi-maser mode. The LDAP servers are behind an LVS director. I also use wrr and set the weights to 250000, >1, 1, 1. As long as the primary server is running clients will connect to it and the primary LDAP server will replicate to the other >three servers. If the primary is down, clients will connect to the other three equally. >I am not using all four servers at the same time because the OpenLDAP muti-master replication is not very reliable in my experience. >Essentially, I am using LVS to make the LDAP service highly available. It has been working really well for me. > This was my first idea too. I set the weight for the primary webserver to 65000 and for the backup webserver to 1. I waited a adequate time to see if the effect I wished become true. But there were still new connections on the lower weighted webserver. I think I read (don't remember where) in the documentation about lvs, that the combination of the source ip of a client and it's target host is 'cached'. So, by setting a higher weight to the primary webserver would not change the behavior of the system at all. Knowing this, the following scenario will end up in a impasse: - you have a configuration were all connections are passed to the high weighted webserver - this webserver is going down - all connections go to the lower weighted webserver - primary webserver comes up again - all connections that were made, in the time the high weighted webserver was down, are still passed to the lower weighted server - you'll end up with splitted connections This is a situation we want to avoid because at least we have to reboot our lvs directors... Maybe I am wrong about the behavior. If so, please let me know. Thanks! Gerd >______________________________________________ >Please read the documentation before posting - it's available at: >http://www.linuxvirtualserver.org/ > >LinuxVirtualServer.org mailing list - [email protected] >Send requests to [email protected] >or go to http://lists.graemef.net/mailman/listinfo/lvs-users _______________________________________________ Please read the documentation before posting - it's available at: http://www.linuxvirtualserver.org/ LinuxVirtualServer.org mailing list - [email protected] Send requests to [email protected] or go to http://lists.graemef.net/mailman/listinfo/lvs-users
