Warm/Cold Standby

[Jim]

We have a simple Genesys enviroment running just TServers, IVR Server, and a GPlus adaptor on a G3 switch. Can someone give me a good explanation of the difference between cold and warm standbys?

I was told a warm standby in our situation would not do us any good. I would think in a cold standby the call TServers could be down for a period of time, but in warm standby you would lose current call data but the standby TServer would be on line immediately.

[Tony Tillyer]

That's pretty much it, in a nutshell. Warm and Cold are both "solutions" within High Availability, however... We had HA for a year or so and the warm TServer kept kicking in, due to the apparent lack of network speed between the primary TServer and it's components...

We took it out as a bad job.

Hope this helps?

Tony

[Jim]

Thanks,

Do you know if Genesys charges for an extra license? Say if I have a server that is loaded with the Tserver software but not in production and not even tied into the network so I can manually switch over to that server if needed? I know I could order a license, but that takes a bit of time. Would rather have it all ready to go.

[OCS]

Some more details.
Genesys TServer redundancy modes.

Cold standby.
Two TServers configured identically, with the exception to host , port and logging settings. One and only one is up and running at a time.
Pros.
Allows quick recovery from hardware or software failure on one of the TServer boxes. Reasonable to use when the switch CTI interface does not allow recource sharing between multiple CTI applications (for instance most of NEC swicthes)
Cons.
All the information about current agent status, call information (connID , parties, etc) and userdata attached to the active calls will be lost upon swicthover.
No support for this mode from Genesys Management Layer.

Warm Standby.
Two TServers configured identically, with the exception to host , port and logging settings. Both are up and running and connected to the switch CTI link at the same time.
One of the TServers runs in primary mode accepts and handles client connections. The other one runs in Backup mode, listens to the switch CTI link , mainteins agent and DN statuses, active call info in its memory. Does not accept client connections.

Cons.
Allows an instant recovery from hardware or software failure on Primary TServer host, including Primary TServer crash.
Upon switchover new primary TServer ready to serve clients immediately as it fully sychronized with the switch up to DN, agent and call statuses.
This mode is fully supported by Genesys Management Layer.
Pros.
New primary TServer does not preserve call connection ID and does not have any user data attached to the calls created prior to the switchover.


Hot Standby.

Two TServers configured identically, with the exception to host , port and logging settings. Both are up and running and connected to the switch CTI link at the same time. In some implementetions requires one or two additional component(s) called HA Proxy. May have required redundant switch CTI Links.
Both TServers should be normally interconnected to each other in order to synchronize internal data up to call connection ID and userdata attached to the call.
Every TServer client seamlesly connected to both TServers.
Pros.
Seamlesly for TServer clients compenstaes for at least single hardware or software failure.
Preserves all DN, agent and call realted information up to call id and userdata.
Fully supported by Genesys Management Layer.

[Dave]

Cold standby, which isn't supported by Genesys (which means Tech Support won't answer any questions about it, and will tell you to remove it if they're trying to resolve a separate problem that it seems to be related to), doesn't really require additional licensing because it's really just a separate copy of the TServer that only runs when the primary one isn't running. The only thing Cold Standby really buys you is the ability to manually switch to another box in the event of a failure of hardware - otherwise, you're really not getting any benefit from it.

Warm standby does require that you purchase the appropriate High Availability option from Genesys. Otherwise the backup TServer/processes won't run because they won't be able to check out licenses for the DNs it's monitoring.

[Jim]

Thanks for the info everyone!

[Vic]

I think Dave put it together pretty much, so in a nutshell
cold standby manual switchover only. Not supported by Genesys but free
warm standby manual and automatic switchover. Supported by Genesys but not free (used to be though...)

Regarding cold standby you still can create a reaction in SCI which will startup your coldstandby TServer in case the primary goes down.

With warm standby, you lose the current call information, but since TServer is automatically started when the other one fails, the new calls are not affected (well, it is not really true, because TServer startup time will take some time and if you are using URS it will be even longer.

By the way, can someone please refresh me on DN egistration?
I do recall this faint memory that in warmstandby backup TServer pre egistered DNs to save on the startup time... Is it still true ?

Thanks,
Vic