The term scale up typically means improving the performance of one node, such as adding more cores and memories. And scale out means adding more nodes in the system, such as using more web servers and database servers.
There are trade-offs betweens these two approaches, usually scale out would make things more complex, such as in this example, consistency issues and extra storage. While scale up could be expensive and limited, but not adding complexity to the network.
It seems to me that there is an analogy, scale up is like improve the performance of single computer, such as OoO, superscaler etc. While scale out is like multi-core processors and parallelize the work.
This comment was marked helpful 6 times.
mchoquet
One interesting (and unintuitive) point to make here is that scale-up parallelism leads to lower request latency than scale-out parallelism does. For example, suppose you have one machine handling a request stream, and the request rate doubles; adding a second machine allows you to serve requests with the same average latency as the original system, while doubling the speed of your machine halves the average latency. You can learn more about this in 15-359.
The term scale up typically means improving the performance of one node, such as adding more cores and memories. And scale out means adding more nodes in the system, such as using more web servers and database servers.
There are trade-offs betweens these two approaches, usually scale out would make things more complex, such as in this example, consistency issues and extra storage. While scale up could be expensive and limited, but not adding complexity to the network.
It seems to me that there is an analogy, scale up is like improve the performance of single computer, such as OoO, superscaler etc. While scale out is like multi-core processors and parallelize the work.
This comment was marked helpful 6 times.
One interesting (and unintuitive) point to make here is that scale-up parallelism leads to lower request latency than scale-out parallelism does. For example, suppose you have one machine handling a request stream, and the request rate doubles; adding a second machine allows you to serve requests with the same average latency as the original system, while doubling the speed of your machine halves the average latency. You can learn more about this in 15-359.
This comment was marked helpful 1 times.