Provide Redundancy With Load Balancing
This can be accomplished by selecting fixed weighting as the Scheduling Method of the Virtual Service. This will allow clients to only connect to the highest available weighted Real Server. If the preferred Real Server becomes unavailable, the next highest available weighted Real Server will be selected.
All weights of the Real Servers must be different. To modify the associated weight of a specific Real Server, follow the steps below in the Web User Interface (WUI):
- In the main menu, select Virtual Services and View/Modify Services.
- Click the Modify button on the relevant Virtual Service.
- Expand the Real Servers section.
- Click the Modify button on the relevant Real Server.
- Change the weight of the Real Server in the Weight field.
If you are using fixed weighting scheduling method and the server with the highest weight goes down, the other server will start to receive all the connections. Once it is back up, the highest weighted server will start to receive ALL connections. There is no way to prevent it from taking over and 'slow start' will not work on fixed weighting.
Ok, thanks for the info. Is there a away to achieve said scenario with another scheduling method? So active/standby setup, where the primary won't take over once its back up.
The closet thing you could do as for a scheduling method would be to use least connection and use 'Slow start'. This will throttle connections when that server comes back up, but some still go there.
Another way would be to use our GEO function though. Inside that it has an option for failure delay, and you can set this to be automatic or manual. Manual will wait for the user(you) to enable the FQDN/site again for connections to go there. This will require a bit more configuration though and probably best to contact Kemp support. I can open up a ticket for you if you wish or you can do one when/if you want to proceed.
Alright, thank you for enlightening me :) I will have a look at the GEO function. I'll open a ticket myself if I need one. Thanks again!
What if the server with the highest priority comes back up? Will it take over? Is there a way to prevent the primary from taking over?