Forum Discussion
Robert_Sutcliff
Nimbostratus
NimbostratusRatio and Slow Ramp Time
Hi,
Does changing the Ratio of a pool member have an immediate effect, or is it gradually applied using the "Slow Ramp Time" configured for the pool?
We periodically do stress testing of some of the servers in for our production site (especially when trialling new hardware). To do this we raise the "Ratio" value from 10 (our default) to some other value (eg. 20) for the pool member we are testing - to see what affect this has on the server (application stats, cpu/memory usage, response times, database, etc).
Once we've gathered our test stats we increase the Ratio and test again.
Once the test is complete we set the Ratio back to normal
We have a Slow Ramp Time of 60 applied to the pool.
We don't disable/enable the pool member being tested
I'd like to confirm(?) that increasing the Ratio has an immediate effect, and is not delayed by the Slow Ramp Time. This will determine whether we need to add delays into our test plan, while the Ramp takes effect, before the next test.
Does anyone know if this is definately the case?
Cheers,
Rob
L4L7_53191Rob: Slow ramp really only applies to new pool members or disabled/re-enabled members. Its purpose is to gradually add connections to the new pool member over time, and it's mostly geared toward any LB method that has least connections as a component.
For example, if you're using least connections and you add a new member to the pool, it'll get slammed with new traffic because the LTM will see it has no connections. Slow ramp will smooth this out over time so the new system won't get overrun with connections all at once.
For your specific scenario I don't think you'll be affected by slow ramp at all. Instead, I'd expect any *new* connections from your load tests to honor the new ratio and any existing connections in service to run as they were before the change.
If anyone has any other input/corrections on this please post.
-Matt