Setup second Dedicated Server for MySQL and EMAIL Hosting for another WHM Server

I did want to expand on the backup mail exchanger idea for emails. As Jared mentioned, you cannot have a cluster for the mail servers, but you could have a setup for each cPanel created account to set it as a backup mail exchanger.

In WHM > Create a New Account area, you'll see this option:

How this works would be that the email machine you have as the primary mail machine (primary MX record) will receive emails normally, and when that machine is down, the cPanel machine will be the secondary MX for the accounts. It would receive the emails during the time the primary MX is down, and then deliver those emails to the primary machine once it's back up again.

In this type of setup, the email accounts would need to be created on both machines (primary MX mail machine and secondary MX cPanel machine).

 

Hello hostmedic,

Multiple cPanel servers can share the MySQL remote database machine, although I am uncertain if I would be able to define easily in describing it. It can be done and it has been done, but usernames cannot conflict in the database.

One solution for Roundcube might be to convert it to SQLite rather than using MySQL in that instance to ensure it doesn't need to use the remote MySQL database, which then leaves only Horde to deal with in that scenario.

To convert a Roundcube database from MySQL to SQLite, it is simply issuing this command on the cPanel machine in root SSH:

Code:

/scripts/convert_roundcube_mysql2sqlite

Thanks.

 

The best solution in this instance is simply to convert Roundcube to SQLite and to remove Horde as a webmail option. I'd already mentioned Roundcube conversion, but most people prefer Roundcube over Horde regardless, so if your users can live without Horde, then simply drop it and convert Roundcube to SQLite.

 

There are different methods to achieve the same purpose to try to get multiple machines to connect to one remote MySQL server. What Ken has stated is sound on the option to keep Horde and simply change the password and re-sync it for all the machines. I personally believe it is easier to not use Horde at all and convert Roundcube to SQLite.

Next, please note that there is nothing in our documentation that states you cannot have multiple MySQL machines connected to a remote MySQL machine. This doesn't indicate we support that setup. If you want to pursue multiple machines to one MySQL machine, you can do it but you will run into some issues that I had already mentioned originally. For example, another consideration would be eximstats and cphulkd also have individual databases. eximstats is going to be skewed for users on both machines and cphulkd will probably need the password re-sync for it as well (if you are using cphulkd on the machines). If cphulkd blocks a user on one machine, that user is going to be blocked on the other machine(s).

The biggest issue beyond the webmail clients; however, is one I already noted that usernames cannot conflict. You would not be able to have a user admin on one machine and another user admin on another machine. If you do, both users will likely be able to see the databases of the other user in their cPanel account due to the wildcard grant for admin_ for cPanel systems with database prefixing, which looks similar to the following:

Code:

GRANT ALL PRIVILEGES ON `username\_%`.* TO 'username'@'%'

As such, you cannot have the same user on multiple machines in this setup.

Ken and I discussed this entire matter prior to my latest reply. As far as I can see, we are simply indicating different mechanisms to use for webmail in the setup you are wanting to try.

Finally, if you do end up trying to achieve this, please only setup two machines for testing it out initially to ensure it works and you are able to see what issues arise. This way you can easily convert back if needed.