EFS works in a very simple and minimalistic way, so as to reduce the amount of configurations that you need to perform and manage as an end user. To start off, EFS provides you with the ability to create one or more filesystems. Each filesystem can be mounted to an instance or instances, and data can be read as well as written to them. Mounting the filesystem requires your instances to have support for the Network File System version 4.0 and 4.1 (NFSv4) protocol. Most Linux operating systems come with the necessary support, however, you may have to install the NFS client on these machines if it is not there to connect to an EFS. So, how is this useful for our WordPress application? Well, for starters, once you have an Amazon Elastic File System in place, you can have multiple EC2 instances connect to it simultaneously and use it as a scalable shared drive that can extend even to petabytes if the need arises. Also, the Amazon Elastic File System does not have any downtime or repercussions if your EC2 instances reboot or even terminate; the data will persist on the filesystem until you manually delete it or terminate the filesystem itself. There are some rules and limitations, however, when it comes to using the Elastic File System, which you ought to keep in mind.
You can mount an Amazon EFS on instances in only one VPC at a time, and both the filesystem and the VPC must be in the same AWS region.
Once the filesystem is created, you will be provided with a DNS name for identifying it within your region. Additionally, you will also be required to create one or more supporting mount targets within your VPC, which basically acts as a connectivity medium between your instances present within a subnet and the filesystem. Here is a representational diagram of how an Elastic File System interacts with EC2 instances using mount targets:
As an administrator, you can create one mount target in each Availability Zone present in a given region. You can also create a mount target in each of the subnets presents within a particular VPC, so that all EC2 instances in that VPC share that mount target. In the next section, we will be exploring a few simple steps required for setting up your own Elastic File System.