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Maximum amount of instances deployed at same time

asked 2015-04-09 17:30:49 -0500

KSoucy gravatar image

What is the maximum amount of instances that can be deployed from Nova at same time?

Is this configurable in nova.conf?

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Do you mean how many instances can be in the processing of creating at the same time?

ethode gravatar imageethode ( 2015-04-09 21:16:21 -0500 )edit

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answered 2015-04-11 02:04:26 -0500 gravatar image

Many factors might impact max concurrency such as controllers' CPU clock speed, the cluster size and network topology. There is max concurrency cap for any given environment. Capacity planning and CLI/API call retry are recommended best practices.

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answered 2015-04-13 03:07:45 -0500

Tobias Urdin gravatar image

Too add upon the answers of the people above, the default number of instances to spawn using the same dialog in Horizon (setting Instance Count) is 48.

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answered 2018-10-10 05:26:59 -0500

manhnt gravatar image

Anyone who still follow this answer or anybody who knows. Please tell me how many instances can lanch at the same time?

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answered 2015-04-10 08:56:25 -0500

jdexter gravatar image

Are you looking to cap the number? you just find out if there is a limit. Either way no, the limit is going to be the physical resources to your environment. In my personal testing in a small 3 node environment, I was able to launch upwards of 120 small vms at once.

What you will see when you reach the limit of your systems is some instances will fail to launch, while the rest launch this tells you that a needed resource was not available during the spawning phase.

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answered 2015-04-13 03:05:28 -0500

There are configurable rate limits: (

Note: nova boot is doing POST, so that is the one you want to fiddle with if you wish to fiddle.

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Asked: 2015-04-09 17:30:49 -0500

Seen: 2,027 times

Last updated: Oct 10 '18