Disk space is relatively inexpensive. However, it's finite. No matter how much disk space you add, users can find ways to occupy it with their files. For example, users who download big files such as movies or ISO files with Linux distributions (hint, hint) may consume several gigabytes of space for each file.
As an administrator, you need to know whether users need more space. You need to know how to regulate the space allowed to different users. As the Linux administrator, you could periodically peruse the files in your users' home directories, and you technically have permissions to edit and even delete users' files. But your users and management might not appreciate that kind of administration; it may even violate corporate policies.
There are a number of things you can do. For example, you can regulate the space associated with user-accessible directories, specifically the /home and /tmp directories. You can configure these directories in dedicated partitions; if one or more users then overload these partitions, the data does not spill over to other parts of the operating system. Conceivably, you can even configure a dedicated partition for a specific user.
The standard Linux method for regulating the space taken by a user uses quotas . Without quotas, users can go wild and load all the space available on your servers.
When you configure a quota, you're regulating either the space or the number of files, as defined by their ...