Comments on: MySQL Switch project

By: mark

mark — Fri, 25 Oct 2013 15:37:31 +0000

Your right a full proxy would be better. And JonV said ScaleArc does what I’m looking for and he is 110% right. I’ve used ScaleArc and it is a dream. I’ve also tried DRDB with HeartBeat for automated failover and MMM and tungsten and more. Most are good and solve a problem. I just want to change servers without touching any application and without changing the MySQL version I’m using. Dreaming? But it’s so vivid.

By: Mark

Mark — Fri, 25 Oct 2013 15:25:25 +0000

Absolutly! ScaleArc for the win! I was even using ScaleArc until a couple of months ago and I would LOVE to have it back! ScaleArc is a DREAM Product. It already does everything I’m wishing for with MySWITCH and so much more. (If you could see me now, picture a cartoon character of me with starts in my eyes reading ScaleArc.)

As for the rest, I think your half right. I’ve done this for other services like DNS and HTTP. It has to be done before the packet is routed in IP-Tables. The receiving server doesn’t care about the MAC address the packet came from? Maybe I could call this thing a MyRouter (I think that’s taken.) Anyway like with routers, the MAC addresses don’t matter.

Source 10.0.0.1 10.0.0.1 10.0.0.1 10.0.0.1 10.0.0.1
Dest 10.0.1.1 –> 10.0.1.1 NAT 10.0.2.1 Route 10.0.2.1 –> 10.0.2.1 Received

The receiver gets the packet and the only thing that is changed is the destination address so it returns the packet back to the source. It would seem a bit confusing that the answer came from a different IP then it was talking to. So yes, this doesn’t work through some stateful firewall’s and routers. Maybe to make this work it would have to do a double NAT and both the source and destination address would have to be fixed and translated or maybe it would have to be stateful. Being a DBA now I’m a little fussy on my TCP-IP so I’ll leave this part at – I made it work before?

By: Mark

Mark — Fri, 25 Oct 2013 14:50:38 +0000

MySQLd_ms is good. Unforchantly, I have applications written in lots more then PHP. If all my programs where PHP I’d still have to go to each application/server and make the change in coordination with the database change.

By: mark

mark — Fri, 25 Oct 2013 14:44:25 +0000

The MySQL proxy project is mostly abandoned. I tested it about two years ago and it wouldn’t even hold up to MySQL slap. I wrote about this in my blog. MySQL Proxy also does a little more the I need. That OK but I’m looking for a switch not a Proxy.

By: Mike

Mike — Thu, 24 Oct 2013 22:01:55 +0000

Is it perhaps similar to MySQL Proxy http://dev.mysql.com/downloads/mysql-proxy/ ?

By: profiles.google.com/10047852389…

profiles.google.com/10047852389… — Thu, 24 Oct 2013 20:30:10 +0000

Check out php.net/mysqlnd_ms which pretty much has all you want but is a driver based approach.

By: JonV

JonV — Thu, 24 Oct 2013 20:24:33 +0000

If you skip your idea of using (almost) direct server return (not changing source address), this already exists; commercially at least. I believe ScaleArc can do this.

Now, the problem with your idea that’s quite similar to direct server return.. it won’t work.

The reply will be coming from an IP that the client making the query has not established a connection with.

You would either need to be a full proxy, or you’d need to do the translation at layer 2 (MAC address). If you do the latter (which is direct server return), you need to leave the destination IP alone and configure the final destination (server mysql is on) to reply to that IP (but not advertise it).

The latter would likely break if you have a stateful firewall between the application servers and the database servers as well.

By: mysqlha.blogspot.com/

mysqlha.blogspot.com/ — Thu, 24 Oct 2013 17:48:26 +0000

I think a good proxy implementation would provide a great foundation for this. However, I am not sure we have that in open source.