e. Examine the File System

After the cluster is created access the cluster by following steps in a. Create HPC Cluster and b. Create FSx Lustre. Connect by selecting the cluster using AWS ParallelCluster UI, wait for a few seconds, and then use the Shell button on the top of the page. Once you’ve connected run

sudo su - ec2-user

to get the familiar user and environment.

Enter

df -h

to ensure the filesystem is mounted at /shared:

Filesystem                   Size  Used Avail Use% Mounted on
devtmpfs                     7.6G     0  7.6G   0% /dev
tmpfs                        7.6G     0  7.6G   0% /dev/shm
tmpfs                        7.6G  584K  7.6G   1% /run
tmpfs                        7.6G     0  7.6G   0% /sys/fs/cgroup
/dev/nvme0n1p1                40G   16G   25G  39% /
172.31.21.145@tcp:/2hwmvbmv  1.2T  7.5M  1.2T   1% /shared
tmpfs                        1.6G     0  1.6G   0% /run/user/1000
tmpfs                        1.6G     0  1.6G   0% /run/user/0

You’ll see a line like 172.31.21.145@tcp:/2hwmvbmv 1.2T 7.5M 1.2T 1% /shared showing the size of the filesystem and the mount point.

Next, use the command lfs find /shared to list all the files present. You should see something similar to:

lfs find /shared

/shared
/shared/s3dkq4m2.mtx.gz
/shared/SEG_C3NA_Velocity.sgy

If the file system is empty you might have to wait for the DRA and data reposition import task to reach the state Available. Now, look at the size of your files by listing the content of the /shared directory.

$ ls -lh /shared
total 1.0K
-rwxr-xr-x 1 root root  13M Jun 22 23:26 s3dkq4m2.mtx.gz
-rwxr-xr-x 1 root root 455M Jun 22 23:26 SEG_C3NA_Velocity.sgy

Next, use the command lfs df -h to look at how much data is stored on the Lustre partition for the Metadata Target (MDT) and Object Storage Targets (OSTs).

$ lfs df -h

UUID                       bytes        Used   Available Use% Mounted on
2hwmvbmv-MDT0000_UUID       34.4G        9.8M       34.4G   0% /shared[MDT:0]
2hwmvbmv-OST0000_UUID        1.1T        7.5M        1.1T   0% /shared[OST:0]

filesystem_summary:         1.1T        7.5M        1.1T   0% /shared

Notice that there is a discrepancy between

  • The size of the files ~ 455 MiB
  • The data actually stored on the Lustre partition: ~ 7.5 MiB of content and 9.1 MiB of metadata.

This discrepancy is due to the lazy loading functionality of Amazon FSx for Lustre when it is linked to an Amazon S3 bucket. Only the metadata of the objects is retrieved on the MDT, the actual bytes or content of the files is copied at first read.