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[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk Logical Structures and File Systems | New Technology File System (NTFS) | Other NTFS Features and Advantages ]

Disk Quotas

In the discussion of the new encryption system added to NTFS 5.0, I mentioned how the lack of encryption in early versions of NTFS was a significant weakness in the NTFS security model. Another weakness of NTFS--this one more of a little, nagging annoyance--is that it did not allow for easy management of disk space usage. While competing products like Novell NetWare offered the ability to control how much of the volume was taken by users, this was not possible under NTFS. Under Windows NT, it is possible for any user to use as much of the disk space on a volume as he or she can grab. This can be a serious administrative problem for systems in some organizations that are shared by many users. In theory, a single user could consume all of the available disk space on a server volume--either intentionally or unintentionally.

To correct this situation, Microsoft introduced quota management as a new feature in NTFS 5.0 under Windows 2000. Microsoft had apparently been planning on this feature for some time, since the metadata file required to implement quotas has been present since Windows NT version 3.5, but it only started to be used in NTFS 5.0. As the name suggests, quota management allows administrators to keep track of how much disk space is consumed by each user, and limit space consumption as well.

The quota system implemented in NTFS 5.0 is quite flexible and includes many capabilities: You have the ability to do the following:

  • Set quotas on a per-user or per-volume basis. This lets you limit space used on particular disks, or overall total space use for a person.
  • Set a "limit" level and a "warning" level, or both. The user is blocked from using any disk space above the "limit" level. He or she may use space beyond the "warning" level, but a warning will be generated.
  • Monitor and log events that cause a user to go over the "limit" or "warning" levels.

Of course, disk quotas are an optional feature; it is not mandatory for administrators to use them. Speaking as someone who has used UNIX systems with quotas before, I can state with authority that they are best thought of as a "necessary evil", and used carefully. :^) It can be annoying to have users fail at what they are doing because they have run out of disk space. It is a good idea to institute quotas only if they are really and truly needed. If you do use them, be sure not to make them too restrictive--if you do, not only will your users be inconvenienced, so will you when they call asking to have their quotas increased. :^) Using the "warning" mode may be a good compromise in some circumstances.

Next: Sparse File Support

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