What is the biggest advantage in using multiple web servers as opposed to using many worker processes? Why would it be better to have 5 web servers with 10 worker processes than having 50 worker processes on one web server. Is it just to avoid waiting while the web server figures out what to do with the request(like start a new process, put in queue etc.)? or is there something more?
This comment was marked helpful 0 times.
tliao
@ajindia The throughput on a single machine is restricted to the resources on that machine. If there's too many computationally intensive tasks running on the web server or too many memory intensive tasks, then there will be a noticeable change in the latency of response.
This comment was marked helpful 0 times.
placebo
Amazon's EC2 actually offers this exact architecture by allowing you to create your own server load balancer, and forwarding each incoming request to your servers in sequential order (round-robin). Amazon also offers another tool called CloudWatch that allows you to define alarms for determining when to scale in or scale out your pool of machines (they are automatically booted up or terminated according to your scale in/out policies). Of course, this is all very similar to what we did in Assignment 4.
This comment was marked helpful 3 times.
edwardzh
The term "scale out" is commonly used in contrast to "scale up." Scaling up is the traditional way of replacing a computing element with a more larger, better, more powerful one, whereas scaling out involves using many computing elements, as in the slide about using many web servers.
In terms of database paradigms, in significant part because of cost efficiency, scaling up is more closely associated with SQL and ACID, whereas scaling out is more closely associated with NoSQL and BASE (Basically Available, Soft State, Eventually Consistent), though there are many exceptions - some applications of database technology, such as for banks, may require ACID.
What is the biggest advantage in using multiple web servers as opposed to using many worker processes? Why would it be better to have 5 web servers with 10 worker processes than having 50 worker processes on one web server. Is it just to avoid waiting while the web server figures out what to do with the request(like start a new process, put in queue etc.)? or is there something more?
This comment was marked helpful 0 times.
@ajindia The throughput on a single machine is restricted to the resources on that machine. If there's too many computationally intensive tasks running on the web server or too many memory intensive tasks, then there will be a noticeable change in the latency of response.
This comment was marked helpful 0 times.
Amazon's EC2 actually offers this exact architecture by allowing you to create your own server load balancer, and forwarding each incoming request to your servers in sequential order (round-robin). Amazon also offers another tool called CloudWatch that allows you to define alarms for determining when to scale in or scale out your pool of machines (they are automatically booted up or terminated according to your scale in/out policies). Of course, this is all very similar to what we did in Assignment 4.
This comment was marked helpful 3 times.
The term "scale out" is commonly used in contrast to "scale up." Scaling up is the traditional way of replacing a computing element with a more larger, better, more powerful one, whereas scaling out involves using many computing elements, as in the slide about using many web servers.
In terms of database paradigms, in significant part because of cost efficiency, scaling up is more closely associated with SQL and ACID, whereas scaling out is more closely associated with NoSQL and BASE (Basically Available, Soft State, Eventually Consistent), though there are many exceptions - some applications of database technology, such as for banks, may require ACID.
This comment was marked helpful 0 times.