Mailing List Archive

[lvs-users] Connection Synchronisation for HA
Hello All,

I have two Linux servers configured for High availability using
Heartbeat and everything is working fine.
But few of our applications use RPC calls for communication, which is a
state-ful connection. So when the fail-over happens we need to
re-connect the application since the connection gets terminated.

While checking the internet, I found that *ipvsadm* does Connection
Synchronisation between the servers.
This feature is wonderful; When a stand-by server becomes the active, it
will have all the information about the currently active connections and
will be able to continue to process the requests.

My goal is not achieving Linux Virtual Server and want to achieve HA for
state-full connection.
Please let me know whether the above will be possible using the LVS and
if possible, then can you provide me some tutorial (or) configuration
steps to achieve the same.

Thanks in advance.

--
Regards,
Rajender.M

_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
Send requests to lvs-users-request@LinuxVirtualServer.org
or go to http://lists.graemef.net/mailman/listinfo/lvs-users
Re: [lvs-users] Connection Synchronisation for HA [ In reply to ]
I presume you're looking for something like this:
http://backreference.org/2013/04/03/firewall-ha-with-conntrackd-and-keepalived/

Although they're using keepalived in this example but you still want to get
conntrackd going

On Mon, Dec 8, 2014 at 11:09 AM, M.Rajender <rajender@visolve.com> wrote:

> Hello All,
>
> I have two Linux servers configured for High availability using
> Heartbeat and everything is working fine.
> But few of our applications use RPC calls for communication, which is a
> state-ful connection. So when the fail-over happens we need to
> re-connect the application since the connection gets terminated.
>
> While checking the internet, I found that *ipvsadm* does Connection
> Synchronisation between the servers.
> This feature is wonderful; When a stand-by server becomes the active, it
> will have all the information about the currently active connections and
> will be able to continue to process the requests.
>
> My goal is not achieving Linux Virtual Server and want to achieve HA for
> state-full connection.
> Please let me know whether the above will be possible using the LVS and
> if possible, then can you provide me some tutorial (or) configuration
> steps to achieve the same.
>
> Thanks in advance.
>
> --
> Regards,
> Rajender.M
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
> Send requests to lvs-users-request@LinuxVirtualServer.org
> or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>



--

Jonathan Petersson
Sr. Systems Administrator
Emediate - a Cxense company
+46732001678
jonathan.petersson@cxense.com
_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
Send requests to lvs-users-request@LinuxVirtualServer.org
or go to http://lists.graemef.net/mailman/listinfo/lvs-users
Re: [lvs-users] Connection Synchronisation for HA [ In reply to ]
Thanks for the information.

What you mean to say is that, we can synchronise the connections between
*virtual/firewall* servers only and not between *application* servers.
i.e, servers which acts as intermediate between two machines (client &
internet) and which just forwards the request from one to another server.

Please correct me if i am wrong.


On 12/09/2014 03:31 AM, Jonathan Petersson wrote:
> I presume you're looking for something like this:
> http://backreference.org/2013/04/03/firewall-ha-with-conntrackd-and-keepalived/
>
> Although they're using keepalived in this example but you still want to get
> conntrackd going
>
> On Mon, Dec 8, 2014 at 11:09 AM, M.Rajender <rajender@visolve.com> wrote:
>
>> Hello All,
>>
>> I have two Linux servers configured for High availability using
>> Heartbeat and everything is working fine.
>> But few of our applications use RPC calls for communication, which is a
>> state-ful connection. So when the fail-over happens we need to
>> re-connect the application since the connection gets terminated.
>>
>> While checking the internet, I found that *ipvsadm* does Connection
>> Synchronisation between the servers.
>> This feature is wonderful; When a stand-by server becomes the active, it
>> will have all the information about the currently active connections and
>> will be able to continue to process the requests.
>>
>> My goal is not achieving Linux Virtual Server and want to achieve HA for
>> state-full connection.
>> Please let me know whether the above will be possible using the LVS and
>> if possible, then can you provide me some tutorial (or) configuration
>> steps to achieve the same.
>>
>> Thanks in advance.
>>
>> --
>> Regards,
>> Rajender.M
>>
>> _______________________________________________
>> Please read the documentation before posting - it's available at:
>> http://www.linuxvirtualserver.org/
>>
>> LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
>> Send requests to lvs-users-request@LinuxVirtualServer.org
>> or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>>
>
>


_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
Send requests to lvs-users-request@LinuxVirtualServer.org
or go to http://lists.graemef.net/mailman/listinfo/lvs-users
Re: [lvs-users] Connection Synchronisation for HA [ In reply to ]
Yes, ipvsadm can synchronize the connections table between active and passive servers.

In /etc/ipvsadm.rules, add the following on the active server:

--start-daemon master --syncid 11
--start-daemon backup --syncid 10

And the same, with reverse weights, on the passive server:

--start-daemon master --syncid 10
--start-daemon backup --syncid 11

This will allow bi-directional synchronization between active and passive LVS servers.

HOWEVER - there is a caveat here; the connection synchronization occurs only when a connection is made or updated. So in a scenario where one of the servers is rebooted for whatever reason, you will not be able to do automatic failback since the connections table will be out of sync, and there is no way (that I am aware of) of forcing a sync. You will need to wait for the connections table to synchronize (the time it takes should be equal to the timeout settings of ipvsadm) before you can perform a failback.

--Dan

-----Original Message-----
From: M.Rajender [mailto:rajender@visolve.com]
Sent: Tuesday, December 9, 2014 2:34 PM
To: LinuxVirtualServer.org users mailing list.
Subject: Re: [lvs-users] Connection Synchronisation for HA

Thanks for the information.

What you mean to say is that, we can synchronise the connections between
*virtual/firewall* servers only and not between *application* servers.
i.e, servers which acts as intermediate between two machines (client &
internet) and which just forwards the request from one to another server.

Please correct me if i am wrong.


On 12/09/2014 03:31 AM, Jonathan Petersson wrote:
> I presume you're looking for something like this:
> http://backreference.org/2013/04/03/firewall-ha-with-conntrackd-and-keepalived/
>
> Although they're using keepalived in this example but you still want to get
> conntrackd going
>
> On Mon, Dec 8, 2014 at 11:09 AM, M.Rajender <rajender@visolve.com> wrote:
>
>> Hello All,
>>
>> I have two Linux servers configured for High availability using
>> Heartbeat and everything is working fine.
>> But few of our applications use RPC calls for communication, which is a
>> state-ful connection. So when the fail-over happens we need to
>> re-connect the application since the connection gets terminated.
>>
>> While checking the internet, I found that *ipvsadm* does Connection
>> Synchronisation between the servers.
>> This feature is wonderful; When a stand-by server becomes the active, it
>> will have all the information about the currently active connections and
>> will be able to continue to process the requests.
>>
>> My goal is not achieving Linux Virtual Server and want to achieve HA for
>> state-full connection.
>> Please let me know whether the above will be possible using the LVS and
>> if possible, then can you provide me some tutorial (or) configuration
>> steps to achieve the same.
>>
>> Thanks in advance.
>>
>> --
>> Regards,
>> Rajender.M
>>
>> _______________________________________________
>> Please read the documentation before posting - it's available at:
>> http://www.linuxvirtualserver.org/
>>
>> LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
>> Send requests to lvs-users-request@LinuxVirtualServer.org
>> or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>>
>
>



---------------------------------------------------------------------
Intel Israel (74) Limited

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.


_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

LinuxVirtualServer.org mailing list - lvs-users@LinuxVirtualServer.org
Send requests to lvs-users-request@LinuxVirtualServer.org
or go to http://lists.graemef.net/mailman/listinfo/lvs-users