Redundancy

[cellspam]

hi all,

I need to create redundancy between to servers, if one goes down i need the other to automatically start.

The idea is have on like master and the other one in standby.

Can some one has any idea?

Regards

 

[Annihilannic]

Normally you would leave both servers running all the time and use some high availability cluster software to manage the services they provide. When the primary server goes down the cluster software brings up the service on the standby server.

Something like Red Hat Cluster Suite or Veritas Cluster Server would do that. A description of the concept and some links to that type of software are here:

http://en.wikipedia.org/wiki/High-availability_cluster

Annihilannic.

 

[cellspam]

Thanks bro i will check it.

 

[cellspam]

I have a ssh server i need to have a secondary server in case the primary comes down.

Any idea how to do that?

Regards

 

[Annihilannic]

What do you mean exactly by an "ssh server"? There's no reason why you can't run SSH on both of them.

One thing you may need to do is configure a virtual IP address that can be moved across to the standby server when the primary goes down. That way clients can continue to connect to the same IP address. Is that what you are thinking of?

Annihilannic.

 

[cellspam]

Please Annihilannic


Can you explain me how to configure the virutal ip.

Thanks

 

[Annihilannic]

Have you tried searching the web?

2nd hit on google for "virtual ip linux" is

http://handsonhowto.com/virt.html

Annihilannic.

 

[cellspam]

thanks!!!!

 

[Kozusnik]

See here. Great tutorial.

http://www.howtoforge.com/high_availability_nfs_drbd_heartbeat

Mark

 

[cellspam]

Hi all,

Thanks for all your help but i still have the same issue, i need to have 2 servers with the same config.
First server master.
Secondary server slave and this must be in standby.
If the First server comes down i need that the Secondary server start working, but i need that this secondary server has the same ip that the Master.

Thanks to all.

 

[Annihilannic]

You can only ever have an IP address on one server at a time, hence our recommendation to use a virtual IP address, which you can move from one server to another as the need arises, e.g. when the priamry server goes down.

You need to use some kind of high-availability software to manage the move of the virtual IP address if you want this to happen automatically.

Annihilannic.

 

[lgarner]

Both of the above links deal specifically with setting up virtual addresses for HA.

It should be obvious that the secondary server can't have the same IP address as the master, so you set up a virtual address that is assigned to the server that is active.

 

[Kozusnik]

In the link I sent, on page 3, it explains that heartbeat handles the virtual IP and shows how to configure the servers.

server1/server2:
/etc/heartbeat/haresources:

server1  IPaddr::192.168.0.174/24/eth0 drbddisk::r0 Filesystem::/dev/drbd0::/data::ext3 nfs-kernel-server

Just setting up the virtual ip won't help. You can have both servers publishing the same IP at the same time.

Mark

 

[MoreFeo]

Have a look at:

http://www.linux-ha.org/

And more specific:

http://www.linux-ha.org/Heartbeat

Installed and configured on 2 servers, Heartbeat can do what ou need. In the active server it will configure a virtual IP, and the passive server will monitor the active server. If it detects the active server is down, it will configure the virtual IP in the passive server.

It can also start and stop applications, mount filesystems (local or shared), etc...

It's easy to install and configure, you only need to edit a few configuration files (/etc/ha.d/ha.cf, /etc/ha.d/authkeys and /etc/ha.d/haresources) and you're done.

 

[cellspam]

Morefeo thanks man.