Need some advices for Failover - High-Availability

[pattone]

First of all sorry for my english (I'm from argentine)
I have a server wich I setup with this great guide http://www.howtoforge.com/perfect-se...ot-ispconfig-3
and is working great with a few websites and domains. Now, looking for information for setup a second server (for failover purpose) that will be in another phisical place with another ip and internet connection I found this 2 excelents howtos:
http://www.howtoforge.com/setting-up...n-debian-lenny
http://www.howtoforge.com/setting-up...n-debian-lenny

and I was wondering what about mail server; my server actually have a few domains with somes mails accounts and I want to have a second server not only for web sites, I want a failover system for mail too. Is there a way to setup this??

Thanks in advance

[falko]

You can set up a backup MX: http://www.howtoforge.com/postfix_backup_mx

[pattone]

Thaaanks a lot falko!! With this I can receive mails when my primary server is down... but what about sending mails?? Can I setup a backup mail server to send mails while the primary is down?

Thanks in advance

[nayr]

Just an idea,
since you have 2 separate locations you might consider running something like HA Proxy in the cloud.

get a small cloud server from one of the big guys thats just running a HA-Proxy instance (id choose one w/lowest avail latency to primary site).. point your services to this edge proxy and have it configured to proxy traffic to your primary server and use the other as backup.. if your proxy server is peered better than your primary site than there is a good change the added latency between you and proxy might be less or equal to connecting directly to you for the majority of traffic.

from here for even better availability could be achieved a pair of proxies in a CARP failover setup.

ps: outgoing mail can come from any multitude of servers, you might need to add it to a SPF record if you use them but that is all if you allow it to relay from your network.

Good Luck,
-R

[pattone]

thnaks nayr for your reply... I have a few questions about this:

If I want a second server only for failover because I don't have a lot of traffic in my primary server and only have a few minor sites and mailboxes:

Is this the only way to setup this?

Do you know if there is a howto for this?

The HAproxy for the web servers that are mentioned in the howtos that I sayd above could be useful?

Thanks a lot and sorry for my english!!

[nayr]

you could try something like this:
http://www.howtoforge.com/setting-up...n-debian-lenny

the other solution would be an external DNS provider that can flip the DNS to your backup server when theres an outage detected, not as robust as HA proxy but for a lightly loaded webserver it should be fine.