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Tony Basallo
Tony Basallo

Reputation: 3074

Azure Websites - Scale Up vs. Scale Out

Has anyone seen any analysis or info on when it is ideal to scale out vs. scale up. When does one make more sense than the other.

Currently, 2 small instances will cost the same as one medium under both the standard and basic modes.

Is having 2 small instances and thus 4 GB of RAM, the same as having 1 Medium instance with 4 GB of RAM (but without an SLA); and the same for cores. All the other features are the same.

Does either CPU pressure or memory pressure, two easy metrics, dictate which way to scale?

And, in this case, scaling out does not present an issue as far as apps/sites working on different machines.

Upvotes: 7

Views: 4692

Answers (2)

user3565431
user3565431

Reputation: 160

Having 2 small instances of 1.75 GB each IS NOT the same as having 1 Medium instance with 3.5 GB of RAM. It is better to have a MEDIUM instance because 3.5 GB is now available to applications instead of just 1.75 GB. Also, each OS takes some RAM away approximately 800-900 MB. Having two instances takes RAm of two OS.

Upvotes: 0

Igorek
Igorek

Reputation: 15850

When you can, always try to scale out vs. scale up. Chances of one VM going down due to a reboot/upgrade/etc and having catastrophic downtime are much bigger than 0... while the overhead of running two VM's and load-balancing between them is minimal and chances of you having both VM's down are much much smaller.

In addition if you ever need 3 servers, scaling up with medium servers will not yield the right granularity.

Upvotes: 3

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