File Systems and Transfers

3 minute read

File Systems

The file system in Linux is where you can save data, files, scripts, etc. There are different storage pools based on the path. In Linux you can provide any storage pool from any directory, not like MS Windows systems, where a drive letter is assigned to each storage pool (ie. “C:”,“D:"). This means that by navigating through nested directories, you may find different capacity limits, depending on where you are.

Locations

Most unix system, including Linux, have a common directory hierarchy. The following is called the root level, since it is at the “top” like roots of a inverted tree:

/
|-- bigdata
|-- bin
|-- boot
|-- dev
|-- etc
|-- home
|-- lib
|-- lib64
|-- media
|-- mnt
|-- opt
|-- proc
|-- rhome
|-- root
|-- run
|-- sbin
|-- srv
|-- sys
|-- tmp
|-- usr
`-- var

The two most important directories are /rhome and /bigdata, since this is where your code and data will be stored. These two directories are IBM Spectrum Scale (GPFS) pools, so storage quotas apply. Your home directory lives directly under /rhome and your groups shared storage lives under /bigdata (if extra storage was purchased). These two “bigdata” directories /bigdata/groupname/username and /bigdata/groupname/shared are symlinked (alias/shortcut) to your home directory for convenience, as seen here:

/
|-- bigdata
    |-- groupname (Quota based on purchase)
        |-- username <-------------|
        |-- shared <----------|    |
|-- bin                       |    |
|-- boot                      |    |
|-- dev                       |    |
|-- etc                       |    |
|-- home                      |    |
|-- lib                       |    |
|-- lib64                     |    |
|-- media                     |    |
|-- mnt                       |    |
|-- opt                       |    |
|-- proc                      |    |
|-- rhome                     |    |
    |-- username (20GB Quota) |    |
        |-- shared ---------->|    |
        |-- bigdata -------------->|
|-- root
|-- run
|-- sbin
|-- srv
|-- sys
|-- tmp
|-- usr
`-- var

For more information regarding these locations, and others, visit HPCC Cluster: Data Storage.

Case sensitive

All paths and commands are case sensitive, an uppercase letter is not the same as a lowercase letter.

Path Types

An absolute path is a full path from top to bottom, from the root to the leaf:

/rhome/username/example_dir/example_file

A relative path is a partial path with the current working directory is the starting point:

example_dir/example_file

Commands

Here are many common commands related to files and file systems (run man <command> for more information):

pwd           # Print working directory
ls            # List files in directory
touch         # Make an empty file
mkdir         # Make a directory
cd            # Change to directory
cp            # Copy file[s] from a directory to a directory
mv            # Move file[s] from a directory to a directory
rm            # Remove a file
rmdir         # Remove an empty directory
df            # Check size of storage pool
du            # Check size of file or directory
check_quota   # Check quota for home and bigdata

Note: CTRL+c will cancel a running command

File Transfers

This section has moved to the Data Sharing page.