Multihost for stability

[DBLaci]

The filesystem survives the restart of the mysql server because it reconnects when needed. If at mount time there would be an option to give more than one mysql server (and credentials maybe), and at every time the reconnect tries to connect to the servers in round robin fashion, this could provide some kind of high availability in case the mysql data is replicated.

[skeyby]

That's a good tought. It requires a rethink about the parameters definition - I don't think the command line can handle so much stuff, maybe it's time to switch to a configuration file.

[EdoaLive]

AFAIK if you specify a DNS name with multiple A records, the mysql library should be able to select the "right" IP to connect to each time.
Still not tested this on mysqlfs but it works in other softwares.

[DBLaci]

True story. This multihost ability implementation - as you say - is out of the scope of the filesystem part. BUT the code needs to handle these cases:

• retry connection on mysql (connection) error
• when retrying connection the dns should be used (not the ip) and this will allow to connect to different host.

[skeyby]

Frankly I haven't tried yet the DNS approach, but will do soon.

In the meantime you can obtain the very same result (with a much higher control) by using MySQL Proxy and have, for example the local MySQLfs instance connect to MySQL Proxy on localhost and then MySQL Proxy relay on (multiple, clustered, whatever) MySQL Servers.

MySQL Proxy's footprint is pretty small and it offers a lot of tracking and handling options, like, say, sending all the write operation on a single server and distribute the selects.

[EdoaLive]

Thank you @skeyby, but I think that MySQL Proxy in this case would be a single-point-of-failure, which I'm trying to avoid!