Mounting your cache automatically

You can update the /etc/fstab file in your Amazon EC2 instance after you connect to the instance for the first time so that it mounts your cache each time it reboots.

Using /etc/fstab to mount Amazon File Cache automatically

To automatically mount your cache directory when the Amazon EC2 instance reboots, you can use the fstab file. The fstab file contains information about the cache. The command mount -a, which runs during instance startup, mounts the caches listed in the fstab file.

Note

Before you can update the /etc/fstab file of your EC2 instance, verify that you've already created your cache. For more information, see Step 1: Create your cache in the Getting Started exercise.

To update the /etc/fstab file in your EC2 instance

1. Connect to your EC2 instance, and open the /etc/fstab file in an editor.

2. Add the following line to the /etc/fstab file.

   Mount Amazon File Cache to the directory that you created. Use these commands and replace the following:

   • Replace /mnt with the directory that you want to mount your cache to.

   • Replace cache_dns_name with the actual cache's DNS name.

   • Replace mountname with the cache's mount name. This mount name is returned in the CreateFileCache API operation response. It's also returned in the response of the describe-file-caches AWS CLI command, and the DescribeFileCaches API operation.

   cache_dns_name@tcp:/mountname /mnt lustre defaults,relatime,flock,_netdev,x-systemd.automount,x-systemd.requires=network.service 0 0

   Warning

   Use the _netdev option that's used to identify network file systems, when mounting your cache automatically. If _netdev is missing, your EC2 instance might stop responding. This result is because network file systems must be initialized after the compute instance starts its networking.

3. Save the changes to the file.

Your EC2 instance is now configured to mount the cache whenever it restarts.

Note

In some cases, your Amazon EC2 instance might need to start regardless of the status of your mounted cache. In these cases, add the nofail option to your cache's entry in your /etc/fstab file.

The fields in the line of code that you added to the /etc/fstab file do the following.

Field	Description
cache_dns_name@tcp:/	The DNS name for your cache, which identifies it. You can get this name from the console or programmatically from the AWS CLI or an AWS SDK.
mountname	The mount name for the cache. You can get this name from the console or programmatically from the AWS CLI using the describe-file-caches command or the AWS API or SDK using the DescribeFileSystems operation.
/mnt	The mount point for the cache on your EC2 instance.
lustre	The type of cache.
mount options	Mount options for the cache, presented as a comma-separated list of the following options: defaults – This value tells the operating system to use the default mount options. You can list the default mount options after the cache has been mounted by viewing the output of the mount command. relatime – Maintains atime (inode access times) data, but not for each time that a file is accessed. With this option enabled, atime data is written to disk only if the file has been modified since the atime data was last updated (mtime), or if the file was last accessed more than a certain amount of time ago (one day by default). relatime is required for automatic cache eviction to work properly. flock – mounts your cache with file locking enabled. If you don't want file locking enabled, remove this mount option. _netdev – The value tells the operating system that the cache resides on a device that requires network access. This option prevents the instance from mounting the cache until the network has been enabled on the client.
x-systemd.automount,x-systemd.requires=network.service	These options ensure that the auto mounter does not run until the network connectivity is online. Note For Ubuntu 22.04, use the x-systemd.requires=systemd-networkd-wait-online.service option instead of the x-systemd.requires=network.service option.
0	A value that indicates whether the cache should be backed up by dump. This value should be 0.
0	A value that indicates the order in which fsck checks caches at boot. For caches, this value should be 0 to indicate that fsck should not run at startup.