Disk quotas are tracked on a per-user, per-volume basis; users are charged only for the files they own. Quotas are tracked per volume, even if the volumes are different partitions on the same physical hard disk. However, if you have multiple shares on the same volume, the quotas apply to all shares collectively, and a user's utilization of all shares cannot exceed the assigned quota on that volume.
In the Properties dialog box, the Quota tab allows the administrator to perform the following tasks:
Enable or disable disk quotas on a volume.
Prevent users from saving new data when their disk quota is exceeded.
Set the default disk quota warning level and disk quota limit assigned to new volume users.
View disk quota information for each user from the Quota Entries view.
Disk quotas track and control disk space usage for volumes. Administrators can configure Windows 2000 to perform the following tasks:
Prevent further disk space use and log an event when a user exceeds a specified disk space limit.
Log an event when a user exceeds a specified disk space warning level.
When you enable disk quotas, you can set both the disk quota limit and the disk quota warning level. The limit specifies the amount of disk space that is allocated to a user. The warning level specifies when a user is nearing the limit. For example, you can set a user's disk quota limit to 50 megabytes (MB), and the disk quota warning level to 45 MB. The user can store no more than 50 MB of data on the volume; if more than 45 MB are stored on the volume the disk quota system can log a system event.
When you enable disk quotas for a volume, volume usage is automatically tracked for new users, but existing volume users have no disk quotas applied to them. To apply disk quotas to existing volume users, add new quota entries in the Quota Entries window.
For more information about setting disk quotas, see Windows 2000 Professional Help.
Disk Quotas and Free Space
Disk quotas are transparent to the user. When a user asks how much space is free on a disk, the system reports only the user's available quota allowance. If the user exceeds this allowance, the system indicates that the disk is full.
To obtain more disk space after exceeding the quota allowance, the user must do one of the following:
Have another user claim ownership of some files.
Have the administrator increase the quota allowance.
The following conditions apply when you use disk quotas:
Disk quotas set on a volume apply only to that volume.
Disk quotas cannot be set on individual files or folders.
Disk quotas are based on uncompressed file sizes. You cannot increase the amount of free space by compressing the data.
If the computer that hosts the volume with a quota is configured as a multiple-boot system with Windows 2000 and Windows NT 4.0, the quota is not enforced and can be exceeded when it is running Windows NT 4.0. However, when that computer resumes running Windows 2000, users who exceeded their quotas must delete or move files to a different volume — that is, until they are under their limit — before they can store new files to the quota volume.
To support disk quotas, a disk volume must be formatted with NTFS. Volumes formatted with previous versions of NTFS are upgraded automatically by Windows 2000 Setup.
To administer quotas on a volume, you must be a member of the Administrators group on the computer where the volume resides.
If the volume is not formatted with NTFS, or if you are not a member of the Administrators group on the local computer, the Quota tab is not displayed on the volume's Properties page.
Disk Quota Limits
The disk space used by each file is charged directly to the user who owns the file. The file owner is identified by the security identifier (SID) in the security information for the file. The total disk space charged to a user is the sum of the length of all data streams; property set streams and resident user data streams affect the user's quota. Since compressing or decompressing files does not affect the disk space reported for the files, quota settings on one volume can be compared to settings on another volume.
The following are types of disk quota limits.
Warning threshold You can configure the system to generate a system log file entry on the computer hosting the volume with the quota when the disk space charged to the user exceeds this value. The user is not notified when this threshold is surpassed.
Hard quota You can configure the computer hosting the volume with the quota to generate a system log file entry or deny additional disk space to the user when the disk space charged to the user exceeds this value.
NTFS automatically creates a user quota entry when a user first writes to the volume. Entries that are created automatically are assigned the default warning threshold and hard quota limit values for the volume.
Disk Quotas States
The administrator can turn quota enforcement on and off. There are three quota states, as shown in Table 17.6.
Table 17.6 Disk Quota States
Quota usage changes are not tracked, but the quota limits are not removed. In this state, performance is not affected by disk quotas. This is the default state.
Quota usage changes are tracked, but quota limits are not enforced. In this state, no quota violation events are generated and no file operations fail because of disk quota violations.
Quota usage changes are tracked and quota limits are enforced.
Administering Disk Quotas
Disk quotas monitor volume use to prevent users from affecting others' use of the volume. For example, if a user saves 50 MB on a volume on which each user has been allocated 50 MB of space, some of this data must be moved or deleted before additional data is written to the volume. Other users can continue to save up to 50 MB of space on that volume.
Disk quotas do not prevent administrators from allocating more space than is available on the disk. For example, on a 8-GB volume that is used by 100 users, each user might be allocated 100 MB of space.
Disk quotas are based on file ownership and are independent of the location of the files on the volume. If a user moves files from one folder to another on the same volume, volume space usage does not change. If the user copies the files to a different folder on the same volume, the available volume space usage against the quota for that user decreases by the number of bytes copied.
The administrator can set default quotas for the volume or for specific users on a volume. A new user receives the default quota unless the administrator established a different quota for that specific user. The administrator can view the level of quota tracking, the default quota limits, and the per-owner quota information by looking at the Quota tab on the Properties dialog box for the volume. The per-user quota information contains the user's hard quota limit, warning threshold, and quota usage.
If you do not want to use the default disk space limit and warning threshold values for a particular user, use the New Quota Entry feature to set up quota thresholds and limits before the user writes data to the volume.
User quota entries cannot be deleted if a user owns files on the volume; all files owned by that user must be deleted or moved to another volume, or ownership of the files must be transferred to another user.
Enabling Disk Quotas
When you enable quotas on a volume that already contains files, the space used by all users who have copied, saved, or taken ownership of files on the volume is calculated. The quota limit and warning level are then applied to all current users and new users. You can then disable or set different quotas for specific users. You can also set quotas for specific users who have not yet copied, saved, or taken ownership of any files on the volume.
For example, you can set a quota of 50 MB for all users of share \\Workstation1\Public, while ensuring that two users who work with larger files have a 100-MB limit. If both users have files stored on \\Workstation1\Public, open the Properties dialog box for that volume, click Quota , click Quota entries , select both users, right click, and then click Properties to set their quota limit to 100 MB. However, if either user does not have files stored on the volume, use the Select Users property sheet to set their quota limit higher than the default for new users.
Local and Remote Implementations
Disk quotas can be enabled on both local computers and remote computers. On local computers, quotas can limit the amount of space available to users who log on to the local computer. On remote computers, quotas can limit volume usage by remote users. The remote computer must be formatted with the version of NTFS included with Windows 2000 and be shared from the root folder of the volume. You need Administrator rights to enable, disable, or manage quotas.
You can use quotas to ensure the following:
Disk space on public servers is not monopolized by one or a few users.
Users do not use excessive disk space on a shared folder on your computer.
Information technology (IT) budget dollars for mass storage are managed efficiently by making users account for the use of shared disk space, by using public disk space only for necessary files.
System files are included in the total sum of volume usage of the person who installed Windows 2000 on the local computer. When implementing disk quotas on a local volume, make sure to take into account the disk space used by these files. Depending on the free space available on the volume, you might want to set a high quota limit or no limit for the user who installed the operating system.
Auditing Disk Space Use
Enabling quotas causes a slight increase in server overhead and a slight decrease in file server performance. By periodically enabling and disabling quotas, you can take advantage of the auditing capabilities provided by Windows 2000 disk quotas without permanently affecting performance.
To create a record of the audit, save a copy of the system log data from Event Viewer to a comma-delimited file that can be read by applications such as Microsoft Excel. These files can be useful for analyzing the data captured.
Exceeding Disk Quota Limits
When you select Deny disk space to users exceeding quota limit on the Quota tab of the Properties dialog box, users who exceed their limit receive an insufficient disk space error and cannot write additional data to the volume without deleting or moving files. Individual programs determine their own error handling for this condition. To the program, it appears that the volume is full.
By leaving this option cleared, you can allow users to exceed their limit. This is useful when you do not want to deny users access to a volume, but want to track disk space use. You can also specify whether or not to log an event to the volume host computer's system log when users exceed either their quota warning level or their quota limit.
Event Viewer builds a historical, chronological record of users who exceeded their quota warning level and quota limit, and when they exceeded them. However, it does not provide information about which users are currently over their quota warning level.
For more information about enabling disk quotas, see Windows 2000 Professional Help.