[Users] High Availability Setup

[Mike Williams]

I just posted a question about MySQL failure in the forums. Check it out 
here:
http://www.voipuser.org/forum_topic_3853.html

samuel wrote:

>Hi verybody,
>
>WARNING: Long e-mail.....
>
>I just started learning how to set up a "classical" configuration with
>load balancer, DB backend and so on....I was reading several threads
>of the mailing lists but since I am a begginer I would need some help
>and clarifications. Apologies if my questions have been solved before.
>[I read Greger and Granig (and more people, I guess) are working (?)
>on a document describing what I try to explain in the follofwing
>lines. I would like to know if you are on it or commercial strategies
>forced you to leave it...as it seems that HA setups are high
>confidential ;)]
>
>I'll try to draw what I have guessed from the threads and other literature...
>
>                                          [SER1]
>	[LB1]		[SER2]
>			     .		[DB (mysql cluster)]
>	[LB2]		     .
>			[SERn]
>
>LBi are the front-end load balancers.
>SER: do I have to say what are these?? (either openSER/SER. I will use
>the name SER for simplicity but I refer to both)
>DB: I placed mysql cluster because it seems to be the most common backend...
>
>Let me make an overview...
>
>Load Balancer
>For LB, it seems that dispacther module can be used. (I don´t remember
>who proposed to dispatch REGISTER with To: and INIVTE with Req-URI,
>why not using Call-ID?? For distributing the registration of a given
>user between several registrars?). Dispatcher module does not have
>failover in case SERi fails so somebody propose to use lcr. Using lcr
>module provides failover but does not guarantee to balance to the
>right instance of SER so I think the only option is to use dispatcher.
>Alternatives:
>Please correct me if I am wrong but there isn´t yet an LVR
>implementation being Call-ID aware....
>DNS SRV records...lack of implementation in end-points and not NAT-friendly..
>
>In order to provide high availability, I tried linux-ha between the 2
>LBi for simplicity although it has some wasted resources. Is it worth
>to give a try to other IP failover aplications (anycast, quagga/bgp,
>vrrpd)?
>Anyone with more experience can comment their use??
>
>
>SIP proxy
>SER....just a matter of taste what you want to use, SER or openSER....
>I read about the cacheless usrloc patch but I could not find it on
>CVS...has it been integrated into the head branch??? has it been
>deprecated because of ...(please fill in the reason)?
>
>
>DB Backend
>For the DB backend...I am going to comment mysql clustering...I am
>using now 4.1.11 because it was already installed. Is it recommended
>to upgrade?? I tried setting the management node, a couple of data
>nodes, and I was trying to set a linux-ha configuration with ip take
>over for the mysql api node (is it possible??) but unsuccessfully:
>When the preferred mysql api node falls down, SER detects the
>connection is closed and all further requests are replied with
>"Internal Server Error" although the secondary mysql api has overtaken
>the service IP and ser database is properly populated.
>Is it possible to make SER reconnecting on mysql failure??  It
>reconnects to the preferred server once it comes back to live but it
>is impossible to connect to the secondary....
>As you might have guessed I am a total begginer with mySQL...
>
>Thank for reading until this line, all kinds of comments are wellcome,
>
>Samuel.
>
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