We're considering hosting a web application on Amazon AWS. I've drawn a proposed setup for it, which I will try to summarize in a few lines:
- The web application is served from webservers in 3 Availability Zones behind a loadbalancer. The webservers are automatically scaled up from 3 when the load increases. This is done through a user data file that runs a few bash commands.
- The database is placed on a Multi-AZ RDS solution
- Because the application writes to the file system, we also need to mount some kind of network attached file system on the webroot.
The last bit is what worries me. I have some experience with AWS and besides dealing with the latency between two Availability Zones, this would provide a single point of failure.
So, I've been looking at GlusterFS, because that's what someone on serverfault suggested to someone who was dealing with a similar pickle. I've been setting up an environment with a Gluster node in every AZ. In the startup script for my webservers, I evaluate the name of the AZ it's in and pick the Gluster node that's in the same AZ, to reduce latency. That's perfect!
But let's say the node in AZ
us-east-1a fails somehow. Is there a way to get my webservers in
us-east-1a to fall back to the node in
us-east-1b if the node in
us-east-1a is unavailable? And, of course, if both are unavailable, also to
So far, I've only seen examples of people using the server and client functionality of Gluster on the same machines, which I'd like to avoid. It's probably good to note that I will be using the NFS client for performance reasons.
Of course, any other suggestion for this file storage system would be very welcome.