[Asterisk-Users] fault tolerant asterisk system

[Andres Tello Abrego]

But those configuration doesn´t mean fault tolerancy.

When implementing a load balancing cluster, failovering is only achieved 
using information replication on line...

If you don´t make some how the information persistant, then you will no 
be to take over the failed server. You will only be providing a High 
Availability solution, instead a failovering.

For example, lvs used to load balance http/https connection in a php or 
java environment. The session information, used to authenticate or 
mantain persistance between transactions is replicated from one cluster 
node to the other, this give a HUGE overhead between the intra-cluster 
communication link (maybe a separated network), with this session data 
replication, when a server fails, and is take over another server, all 
the information about what was doing the user, is also available at 
replacement server, so, the comunication continues, integrity is 
mantained, etc... Lvs also have a persistent mode, which make, all 
communications coming from the same IP, are redirected to the "last" 
server, for a configurable amount of time.

Lvs can be used to load balance sip/iax connections, but failovering, 
with the HA proyect, means that is a server goes down, that means that 
the ALL comunications will fail, pots fxo lines will obviously hangup 
and all IP communitacion will fail also, becose the asterisk taking over 
does not have the register info or the state of the comunication 
channel, channels will need to re-register, etc...

You can have some registration info at a mysql server, but then, now you 
have anoter point of failure and then you will need make a cluster and 
failover strategy for the mysql (1 master to 1 slave replication can do 
the trick)... but then again, to have full failover, we need to share 
the state of, at least, the IP channels...

Full failover at least for IP communications, is a tricky issue.

Having High Availability, LVS + HA, and the trick is done. Also a 
duplicated amount of telephony hardware, that Digium will thanks :)


Nathan Alberti wrote:
> http://voip-info.org/tiki-index.php?page=Asterisk%20High%20Availability%20Solutions 
> 
> 
> Infocus wrote:
> 
>> Good idea.  A few more questions:
>>
>> I want to have one asterisk box roll over to another if it goes down 
>> for any
>> reason.  I heard there is a way to monitor the IP in case such an event
>> occurs.
>>
>> How does asterisk provide the failover mechanism?
>>
>> Could someone explain how to achieve this project?
>>
>> Thanks again. 
>>
>> -----Original Message-----
>> From: asterisk-users-bounces at lists.digium.com
>> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Matt
>> Sent: Tuesday, April 05, 2005 5:26 AM
>> To: Asterisk Users Mailing List - Non-Commercial Discussion
>> Subject: Re: [Asterisk-Users] fault tolerant asterisk system
>>
>> mmm one other thought.. the load balancing switch needs to support A)
>> failover and B) stream assocciation (so that it keeps you on the same
>> * server as long as you are sending packets!)
>>
>> On Apr 5, 2005 8:25 AM, Matt <mhoppes at gmail.com> wrote:
>>
>>> I would say if you want true redundancy.. rsync your files on each
>>> system.. have RAID on each system, and use a load balancing switch.
>>>
>>> Incidentally... infocus@?  Nortel? (eek did I just utter a bad word?)
>>>
>>> On Apr 5, 2005 7:53 AM, Infocus <infocus at todave.com> wrote:
>>>
>>>>
>>>>
>>>> I am looking to create an asterisk system with failover in case one
>>
>>
>> asterisk
>>
>>>> box fails.
>>>>
>>>>
>>>>
>>>> Current hardware:
>>>>
>>>>
>>>>
>>>> 2 asterisk boxes (P3 950mhz gateway server and an older dell) w/128MB
>>
>>
>> RAM
>>
>>>> each, latest release of asterisk/centos.
>>>>
>>>> 1 RAID5 server with 2 SATA HD's
>>>>
>>>>
>>>>
>>>> Goals:
>>>>
>>>> I want Asterisk to take over active calls when one server fails.  I may
>>>> want to store data (config files, voice mail, etc.) on the RAID server.
>>>>
>>>>
>>>>
>>>> What do you all think about this arrangement. my only concern is if my
>>
>>
>> RAID
>>
>>>> server goes down, both asterisk clones become unusable. Would I be
>>
>>
>> better
>>
>>>> off storing files on one asterisk box and then rsync with a cron job
>>
>>
>> every 1
>>
>>>> minute?  Would it be better to have both servers running at the same
>>
>>
>> time
>>
>>>> and processing calls, with the data stored on the server?
>>>>
>>>>
>>>>
>>>> A side question would be: if one asterisk box got overloaded with 
>>>> calls,
>>>> could it roll over to the second box?
>>>>
>>>> Thanks for the advice/opinions, in advance!
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>
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