Disk Quotas - 16 Dec 2002

To recoin a phrase, there's no such thing as being too thin, too rich, or having too much hard disk space. The price of disk storage has decreased steadily in recent years, and adding disks to corporate file servers to accommodate increasing storage needs is now a viable option. However, even if you have a sufficient budget for adding storage space, managing disk expansion can be tedious. You must monitor disk use, install disks as needed, change pointers and mappings to move users to the new disks, and establish backup procedures.

When administrators grow tired of performing these chores and decide to investigate disk usage in their organization, they often find volumes filled with unnecessary data files, including outdated documents, personal files (e.g., large graphic and audio files), and other nonessential data. Disk-usage policies are rarely effective because enforcement is so time-consuming.

Windows 2000 introduces disk quotas, a great solution that lets you dump the disk-space problem into the laps of your users. When you enable quotas, each user receives a finite number of bytes of available disk space. Users who reach their quota, encounter a problem when they try to work with files, which provides an enormous incentive for them to purge unnecessary or unauthorized files.(To learn what actions add bytes, see the sidebar "How the System Counts Bytes," page 60.)

If you don't know about disk quotas, or if you've heard the term but didn't realize how effective and uncomplicated this feature is, read on. I tell you how to set up and configure an efficient and fair quota system for your users and perform the administrative tasks necessary to maintain and enforce the quotas you set.

Turning on Disk Quotas
You almost certainly meet the two requirements for enabling Win2K disk quotas on your system: You must use an NTFS-formatted hard disk, and you must have administrative rights on the target computer. Note that I didn't specify Win2K Server—you can also establish disk quotas on Win2K Professional machines. In fact, if your users save documents locally on Win2K Pro machines, establishing disk quotas is a way to force users to perform housekeeping chores regularly and to dissuade them from downloading large files from the Internet.

Establishing quotas is simple and straightforward:

Setting Default Limits
To activate fields for disk-space limit and warning levels, select Limit disk space to and Set warning level to, as Figure 1, page 60, shows. Enter the values you require for disk-space limits and warning levels (you can use decimal values—for example, 35.5), then select units of measure (KB, MB, GB, TB, PB, or EB) from the drop-down lists. Be sure the specification for the warning level is slightly lower than the disk-space limit.

The specifications you enter in this dialog box become the default settings, and the system automatically applies these settings to all users who access the hard disk. However, as I discuss later, you can customize the disk-space limit and warning level specifications for individual users.

Denying File Saves
Select the Deny disk space to users exceeding quota limit check box if you want to prevent users from writing to the disk when they've reached their quota. Users then receive an error message from the application they're using when they try to save a file because the application sees the volume as full. Users must create free space on the disk before they can save a file.

Denying disk space to those who have reached quota limits is the most effective way to prevent users from wasting space. However, be aware that if you choose this option, you'll hear from users. You can temporarily enlarge a user's quota (see the section "Configuring Customized Quota Entries"), but other users will likely find out and ask for the same favor. You can also point out unneeded files the user has stored. On a positive note, I've learned from administrators who have taken a strict approach to quotas that this state of affairs doesn't last long. Eventually, users understand that you mean business, they make disk housekeeping a regular task, and the complaining stops.

Set Logging Options
Instead of denying write privileges when users reach quotas, you can log events when users exceed either their quota warning levels, their disk-space limits, or both. The system writes these events to the local computer's System log, which you can view in Event Viewer.

Technically, you don't have to log events instead of denying write privileges—you can set logging options in addition to denying write privileges, but doing so is unnecessary. You log events so that you can track users who exceed quotas, but denying write privileges prevents users from exceeding quotas.

Also, you can set logging options to track both the warning level and the disk-space limit, but you should set only one of these options. Otherwise, you double the number of events you collect in the System log without gaining any advantage in your efforts to control disk-space use. Decide whether to notify users when they get close to using too much disk space (i.e., with the warning-level specification) or when they've exceeded their allotted disk-space limit (i.e., with the disk-space limit specification).

Using Event Logs
If you enable logging, you can monitor disk-quota events in the System log and know when to cajole your users. The listings for disk-quota events have the following characteristics:

You can use the Microsoft Management Console (MMC) to work with Event Viewer to check from your computer a remote computer that's running disk quotas. To accomplish this, follow these steps:

MMC displays the remote computer's Event Viewer. Save the console for future use (I recommend that you use the remote computer name as the filename). If you're displaying Administrative Tools on the Programs menu, the console appears in the submenu.

Configuring Customized Quota Entries
Win2K's disk-quota feature lets you set customized quota levels or disable the feature for individual users for whom your default settings are too limiting (e.g., for users who create numerous or large files). To modify the quota settings for a user who has already used the hard disk in question, open My Computer or Windows Explorer, right-click the icon for the hard disk you want to configure, and select Properties. Next, select the Quota tab, then click Quota Entries to open the Quota Entries for Local Disk window. The names of all users who have used this drive to save files will appear, as Figure 2 shows. Right-click a user listing or multiple user listings, and choose Properties. In the Quota Settings dialog box, which Figure 3 shows, change the disk-space limit and warning-level specifications or disable quotas for this user. If you select multiple users, the title bar says Multiple Users instead of displaying the name of an individual user.

As new users access the drive, the quotas you specified will automatically apply. Alternatively, you can customize individual specifications before new users access the drive for the first time (otherwise, you must change their settings by using the steps I described in the previous paragraph). To customize quotas for users who haven't yet accessed this drive (and for whom you don't want the default settings to apply), perform the following steps: