Backup mail server

[purusrhce]

Hi Linux gurus,

I want to put a backup mail server for my sendmail. If my primary server fails to response then my backup server have to take care of users request. Users request will automatically forward to the backup server for sending & receiving mails. can any one help me on this.

Thanks in advance,
Purushoth

[gr8rcake]

I'd try making your mail server have an alias IP address, in addition to its primary one. When the mail server shuts down, create the same mail alias IP address on the backup server.

The one problem is the ARP tables on your router may have to be cleared so that it can associate the new MAC address of your backup server's NIC with that of the IP alias.

You can do this by sending a ping to the router using the alias IP as your source address.

# ping -I alias-ip-address router-ip-address

You should try it a couple times with a test system to be sure.

[purusrhce]

Hi,

can we make it as an automatic process with the help of dns, if one server fails DNS will redirect the request to backup server with the help of MX Record. Waiting for your reply.

Regards

[gr8rcake]

There are better ways than using DNS to provide redundancy. You still have to write a monitoring script on your monitoring server, update zone files on your DNS server, restart bind. A high DNS TTL value can cause further delays, and occasionally, TTLs are not honored by caching DNS servers.

The IP swapping method is instantaneous.

There is a project called Linux-HA that could help. Their product does monitoring and will automatically flip the mailserver VIP for you (assuming they are on the same network subnet).

This should reduce the amount of scripting and testing you will need to do.