Any advantage to having runtime specs match GCE predefined machine types?
When I specify a combination of memory and cpu that isn't a combination for a GCE predefined machine type, is Terra requesting a custom machine type in GCE?
Does it take longer for a custom machine type to deploy than a predefined machine type? By how much?
Is there a good rule of thumb for the cost savings of using a predefined machine type compared to a custom request?
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4 comments
Hi Jean -
This is an excellent question. I found some info on the Google Cloud website that:
"Google charges for custom machine types based on the number of vCPUs and memory hours that the instance uses. This is different than how predefined machine types are charged, so we recommend you review the pricing page before you create a custom machine type.
Instances running a custom machine type are subject to the same 1-minute minimum charge as any other instance, but sustained use discounts for custom machine types are calculated differently. For more information, read sustained use discounts for custom machine types."
So it seems that preconfigured machines have a lower cost than custom machines. It really depends on the task. If the custom machine is run for a long time, it may have a significant impact on overall costs. if it is just needed for a day, it may be just $1-$2 difference.
What are you trying to do that requires a custom configuration?
I have been testing some code on starting clusters, and I see no significant difference in the time, but I think someone would have to test this to benchmark the amount of time it takes to spin up a custom machine versus a standard machine.
When designing a WDL, I'm often just "taking a good guess" at the runtime parameters that I should be requesting in my first draft. I suspect that when I do this I'm often creating a custom configuration for no good reason but didn't know if that might end up costing more. Sounds like I should play with the pricing calculator, unless someone has already done that?
One useful piece of information may be "What is the predefined machine type used in FireCloud when nothing is specified"?
Hi Jean - If I had to guess, I would say it is a n1-standard-4 or a n1-standard-2 machine by default. I will try to find out more details.
Hi Jean -
There is some additional information in the Cromwell documentation here: https://cromwell.readthedocs.io/en/stable/RuntimeAttributes/
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