Define hard disk quotas, and then explain how they are used. Then, describe the differences between soft limits and hard limits.

What will be an ideal response?

If there are several users on a Linux system, there must be enough hard disk space to support the files that each user is expected to store on the hard disk. However, if hard disk space is limited or company policy limits disk usage, you should impose limits on filesystem usage. These restrictions, called hard disk quotas, can be applied to users or groups of users. Furthermore, quotas can restrict how many files and directories a user can create (that is, restrict the number of inodes created) on a particular filesystem, or the total size of all files that a user can own on a filesystem. Two types of quota limits are available: soft limits and hard limits. Soft limits are hard disk quotas that the user can exceed for a certain period of time (seven days by default), whereas hard limits are rigid quotas that the user cannot exceed. Quotas are typically enabled at boot time if there are quota entries in /etc/fstab, but can also be turned on and off afterward by using the quotaon and quotaoff commands, respectively.