Quota-Management Tools

Rein in your space hogs

Network and systems administrators constantly fight the disk-space battle for network storage. Although disk space is fairly inexpensive, the administrative cost of managing large volumes of data can sneak up on an organization. When a file system becomes full, some level of administrative involvement—adding more storage, finding and deleting unnecessary files, or rebuilding a crashed volume—is inevitable. In addition to fixing the immediate problem, the administrator typically needs to identify individuals who consume more than their share of disk space.

Quota-management software takes a proactive approach to space allocation and removes the administrator from the enforcer role when users attempt to use more than their allotted storage. In this comparative review, I look at four quota-management products—WQuinn's QuotaAdvisor 4.1, Enterprise Edition; Northern's Quota Server 5.0c; NTP Software's Quota Sentinel; and Tools4ever's SpaceGuard 4.2—to see how well they manage disk space and how successfully they ease the administrative burden.

What's in Windows 2000?
Out of the box, Windows 2000 Server offers user-based quotas that you can apply to all users or a select group of users. However, as with many Microsoft OS add-ons, the feature's overall functionality falls short of what third-party products can provide.

The most noticeable limitation of Win2K's quota functionality is that it provides no directory quotas and no advanced notification tools. Directory quotas can prevent a disk from becoming full regardless of who writes files to it. Notification tools encourage end users to be proactive about their storage habits and relieve administrators from having to monitor event logs for quota violators. Win2K's built-in quota-management functionality might work for small organizations that experience minimal changes in disk usage, but if you're serious about effectively managing storage on your servers, you need a third-party tool.

The Test Environment
To test the products, I used four custom-built Intel Celeron-based computers. I installed Windows NT Server 4.0 on the first system, NT Workstation 4.0 on the second, Win2K Professional on the third, and Win2K Server on the fourth. Each server was a domain controller (DC) for its own domain, and I configured a two-way trust between the two domains. The two clients were members of both domains. This configuration let me test the products with Win2K and NT installed on both the client side and the server side.

To approximate the needs of a typical organization, I implemented identical quota schemes on both servers. On each disk object, I wanted to establish a quota to manage total capacity utilization. I gave each user account a 100MB quota on its home directory and a 50MB quota for the Files share on the server. In addition, I imposed a 200MB quota on each directory beneath the Files share. To test the products' usability in the arenas of quota implementation, management, and monitoring, I configured the same environment for each product.

Leading the Pack
QuotaAdvisor's features and stability lift the product above the rest of the crowd. QuotaAdvisor excels particularly in the flexibility it gives you for creating quota objects. Whereas most of its competitors require you to know the sizes of your partitions and enter an appropriate value for the quota size (e.g., in bytes, kilobytes, megabytes), QuotaAdvisor avoids the necessity of manual calculation and lets you use a percentage value to specify a quota size. QuotaAdvisor's most obvious drawback is the lack of detail in its instruction manual.

Quota Sentinel lacks some of QuotaAdvisor's flexibility, but I liked the idea of a hierarchical administrative model for managing quotas. Both Quota Server and SpaceGuard are reasonable tools for smaller organizations in which simplicity of administration is important. However, if that simplicity comes at the expense of a feature you need, you might compromise your satisfaction in the long run.

QuotaAdvisor 4.1
I installed QuotaAdvisor from WQuinn's StorageCeNTral CD-ROM. StorageCeNTral is a suite of storage-management products that also includes DiskAdvisor and FileScreen 2000. (Because I wanted to focus on quota-management features, I chose not to install these two products.) When I inserted the autorun-enabled CD-ROM in the Win2K Server computer, an HTML-based installation screen appeared, prompting me to select an installation of the Standard, Enterprise, or Cluster version of QuotaAdvisor. I clicked Enterprise. I then input my license key, from which the installation program determined that I was licensed to install the Enterprise version.

During the installation, the software prompted me for an account with administrative privileges that the QuotaAdvisor services could use. For this purpose, I created an account called QAServer and specified it (along with its password) in the installation dialog box. The software then presented me with options for configuring either a Microsoft Exchange Server or SMTP mail server for distribution of quota notifications to users. I created a mail account called QAServer on an Exchange Server system and specified that account in the dialog box. After the installation process installed the program files, I restarted the computer. An icon for QuotaAdvisor appeared on my desktop.

The Management Station
Clicking the desktop icon opened the QuotaAdvisor Management Station, in which the next phase of QuotaAdvisor's configuration occurred. The Management Station, which Figure 1 shows, is a centralized UI through which you manage and monitor quotas on all connected servers. The UI's left pane provides a treeview of the local computer and computers on the network. In the interest of productivity, the Preferred Machines branch lets you organize frequently accessed computers. The right pane displays the contents of the items that you select in the left pane.

The first time I opened the Management Station, the software's Management Wizard launched. However, I wanted to install QuotaAdvisor on my second server before performing any of the wizard's operations, so I closed the wizard. I followed the user guide's instructions for performing a push-install of QuotaAdvisor to my NT Server system from the Management Station, but the menu option I needed was shaded. I called WQuinn's technical support to determine the cause of this problem. After some troubleshooting, a WQuinn technician determined that I was experiencing a problem with one of the application's DLL files, which affected only QuotaAdvisor installations that aren't installed as part of the Storage CeNTral suite. I received a new DLL file and resumed QuotaAdvisor's installation on the second server.

The push-install resembles a local installation and gives you the option of restarting the installed server upon completion or delaying the restart until an appropriate time. Before running QuotaAdvisor, you must restart the server.

QuotaAdvisor Nomenclature
Before you implement QuotaAdvisor, you need to understand several components and subcomponents of quotas. To create a quota in QuotaAdvisor, you must first create a quota object. A quota object can be any physical portion of a disk, whether it's the whole disk, a share, a directory, or an individual file. To that object, you can apply an absolute quota, a user quota, or a group quota. You use an absolute quota to monitor and enforce disk-space usage regardless of users and groups. User and group quotas apply to an individual user or group, based on file ownership.

You can apply learn-mode quotas to users or directories. When you apply a learn-mode quota to an object, QuotaAdvisor scans the object and applies the quota settings to existing users or directories, based on the type of quota you configure. In addition, when you create a new user account or directory, that account or directory will inherit specific settings from any learn-mode quotas that apply to those objects. To ensure that files placed in lower-level directories apply to the first level's quota, directory learn-mode quotas apply only to first-level subdirectories. For example, if I place a 50MB directory learn-mode quota on a directory named userfiles and create a subdirectory named myfiles, the myfiles directory would have a 50MB quota. Furthermore, if I create a subdirectory beneath myfiles named documents, that subdirectory wouldn't have a directly applied quota—rather, its contents would count toward the 50MB quota on myfiles.

Creating Quotas
To create and manage quotas in QuotaAdvisor, you can use menu selections to manually configure the appropriate objects or you can use the Management Wizard. I attempted to use the wizard to set up quotas for my environment, but the wizard is helpful only for setting up rudimentary quotas that have no detailed configuration.

To manually configure a quota, right-click an object and select New from the resulting menu. You can also use command-line utilities to set, delete, modify, and show quotas. To replicate quotas that I had created on the Win2K Server system to the NT Server system, I took advantage of QuotaAdvisor's replication features. To enable replication, I highlighted the icon representing the Win2K server and chose the Replication object from the Server menu. Then, I specified the NT Server system as the server to which I wanted to replicate quotas.

I configured absolute quotas on my Win2K Server system's C:, D:, E:, and F: partitions. For those objects' quota size, I had the option of specifying an actual byte size, a percentage of total capacity, or a percentage of current usage. I set each object's quota to 90 percent of its total capacity, then set an overdraft quota of 10MB. (The overdraft quota gives end users some flexibility for continued usage of the object after the object reaches the quota.)

Other configurable options include Write Through, Soft Quota (Monitor Only), Send Disk Full Error Code, and Reset Highwater Mark Upon Saving. Write Through lets the quota-offending operation finish writing before the system enforces the quota. Soft Quota (Monitor Only) can monitor a quota without enforcement (although threshold warnings still apply). Send Disk Full Error Code sends a disk-full error code, which can be interpreted by OSs that don't understand the not enough quota error code. Reset Highwater Mark Upon Saving sets a high-water mark (i.e., the point of highest disk space utilization), used for monitoring, to an object's current capacity usage. QuotaAdvisor includes more than 10 sample templates that can help you configure quotas for different situations and lets you save a custom configuration as a template for use on other objects. For my absolute quotas, I chose the Write Through and Reset Highwater Mark options.

I used the same process to create directory learn-mode quotas on the Files share and user home directories and to create user learn-mode quotas on the Files share. For these three quotas, however, I cleared the Soft Quota (Monitor Only) check box so that the system would enforce the quotas. QuotaAdvisor uses an Increase Quota right that lets administrators decide who can add, delete, or modify quotas.

Thresholds and Actions
You can set five threshold levels for a given quota, and you can configure the thresholds to trigger appropriate actions. These actions include sending an email message to the user, displaying a pop-up message, sending a message to the event logs, sending an SNMP trap, and generating threshold-infringement reports. If you want to generate messages, you can choose from a large number of macros that insert realtime information into the message. For example, you can create an automated message that addresses users by name and gives them actual numbers regarding their usage and quota.

You'll find the threshold settings on individually tabbed pages in the Quota Configuration dialog box. I set thresholds for 80 percent, 90 percent, and 100 percent quota utilization and sampled the available actions, which performed as I expected.

Monitoring and Reporting
Space Monitor, a utility you use to view utilization statistics for QuotaAdvisor's managed objects, displays in a separate window within the Management Station. To launch Space Monitor for an object, simply right-click the object and choose Monitor Start from the resulting pop-up menu. If the selected object represents a computer, the resulting window displays space-utilization information for each quota object on that computer. If the selected object represents a quota, the software monitors individual items for the quota. The software adds a Space Monitor icon to the system tray on servers that have QuotaAdvisor installed.

WQuinn markets its DiskAdvisor product for detailed reports, so the reports that the company has built in to QuotaAdvisor are fairly limited. From the Management Station you can view or print a report about an object's usage categorized by user or object. To assist in troubleshooting quotas, you can also set a threshold to generate ASCII, HTML, or comma-separated output for as many as eight noncustomizable reports.

A Thorough Quota-Management Tool
QuotaAdvisor offers an abundance of quota-management options—so many, in fact, that they're distracting. The product's learning curve is somewhat steep, and unfortunately the manual won't help you overcome that curve. I would have benefited from a Getting Started guide and a walkthrough of different quota scenarios. In general, I felt that the documentation lacked information pertinent to first-time users. However, the product is quite configurable and will meet the quota-management needs of any organization.

Overall, QuotaAdvisor is a mature tool, as evidenced by the number of features and options that cater to advanced quota management. The other products in the StorageCeNTral suite contain additional reporting and file-blocking capabilities. Including those capabilities in QuotaAdvisor would further separate this product from its competition.

Quota Server 5.0c
I received Quota Server 5.0 on a CD-ROM, but Northern encouraged me to download version 5.0c so that I had the most up-to-date code. I installed Quota Server first on my Win2K Server system. The installation program options were Custom Installation, Typical Quota Server Server, Typical Quota Server Client, Upgrade Client from 4.x, or Upgrade Server from 4.x. I chose Custom Installation, and the software prompted me to enter an installation path and specify which components I wanted to install; I chose to install all the available components. The software then prompted me to specify an account under which the Quota Server service would run. Rather than use the system account, I chose a specially created account for the service. At the next prompt, I entered a Uniform Naming Convention (UNC)-format path to a Quota Server license file. Then, the software asked me to supply the mail settings I wanted to use for distribution of email alerts. From the drop-down list, I selected and configured Exchange Server. (The drop-down list also included Microsoft Mail—MS Mail—and SMTP.) Finally, I specified a user group that would have the authority to modify and assign permissions to quota objects. After finishing setup, I started Quota Server without rebooting.

Because remote installation is the means for duplicating quotas and reports across multiple servers, I first configured those items on the Win2K Server system. Then, to install Quota Server on my NT Server system, I opened the Quota Server Client from the Start menu and chose Remote Installation Wizard from the Tools menu. The wizard walked me through the steps of selecting a server on which to install Quota Server, setting the installation path, and configuring the service account. The wizard's final step gave me options for copying configuration items and templates from the existing server to the newly installed one. When I clicked Finish, the file-copy process started, but an error occurred while copying the qsfilter.sys file. I contacted Northern's support technicians, who provided me with a patch that corrected the problem.

The Quota Server Client
The Quota Server Client, which Figure 2 shows, is the UI that you use to create, monitor, and manage quotas. The UI is composed of three columns—the Navigation Bar, the Browse Tree, and the Monitor Window—as well as a Properties Toolbar. The Properties Toolbar presents five tabbed pages of quota-configuration options. The toolbar's tabs are General (Quotas), Settings, Thresholds, Notifications, and Custom.

Quota Server's Quota Types
To meet the needs of various environments, Quota Server offers several types of quotas:

Creating Quotas
To enable quota creation and management through right-click menu options, you can invoke the Quota Server Client directly from Windows Explorer. However, for all intents and purposes, the bulk of the software's action takes place within the Quota Server Client UI's Properties Toolbar. You can also set, delete, import, export, and report on quotas from the command line.

When I initiated quota creation from Windows Explorer, everything worked smoothly. However, when I initiated quota creation by selecting a drive from the Browse Tree, I experienced a small problem: The software left a trailing backslash off the path. A Northern representative informed me that a patch was available for this glitch. Alternatively, I could work around the problem by entering the backslash manually.

On the General tab, I entered the server and directory to which I wanted to apply a quota. On the Settings tab, I configured Object quotas for my Win2K Server system's C: partition. The only method for configuring quota size is to manually enter a byte value by using K, M, or G to indicate kilobytes, megabytes, or gigabytes, respectively. At this point, I encountered another problem: Quota Server didn't recognize any data after the decimal point in my entry. For example, when I tried to create a 1.95GB quota, I ended up with a 1GB quota. Also, I had to enter each quota individually. (Some of the other products let you simultaneously configure similar quotas on multiple objects.)

I also created Auto User quotas for the Files share and Auto Dir quotas for the user home directories. Each quota object has a Permission tab, by which you can control who performs specific quota actions. I set the rights to Write for administrators and None for all other users.

Thresholds and Actions
On the Thresholds tab, you can configure three threshold levels. For each threshold level, you can configure settings for Level (i.e., trigger level), Action, User Notify, and Admin Notify. Four types of actions and six types of notifications give you a fair amount of flexibility in automating responses to quota violations.

To provide detailed information to users and administrators in the event of a quota violation, you can use notification templates in conjunction with Quota Server notification variables. These variables contain pertinent quota information that you can insert into a notification message. The Notifications tab lets you target notifications for users and administrators. You can specify multiple recipients for both pop-up and email notifications. Also, to configure actions that execute a program, you specify the program and any parameters. I sampled the types of file and directory locks, along with the various notification methods, to test the program's interaction with end users and administrators. Everything worked as I expected.

Monitoring and Reporting
Quota Server's Monitor Window lists pertinent statistics for each quota and displays a graphical representation of utilization. The Status column keeps track of quota thresholds and provides icon representations for any locks that result from an action based on that threshold. You can sort and filter information in the Monitor Window, and you can save custom views to display information about selected quotas in a specific format.

To configure and schedule reports, click the Reports icon in the Navigation Bar, then right-click inside the Monitor Window and choose New from the pop-up menu. The Properties toolbar's contents change to reflect report settings. You can configure the product to send report output to an ODBC-compliant database, a file, email users, a pop-up message, or the clipboard. You can store output sent to a file in HTML format for intranet publication and easy readability. The reporting features were easy to use and functioned well, but I would have preferred more detailed reporting options.

Simple but Effective
Overall, I found Quota Server fairly easy to use. After I worked through some minor difficulties in setting up quotas, the product performed as I expected. The Monitor Window is one of the product's stronger features. The ability to customize and save views will help administrators more effectively manage quotas. The built-in reporting functionality offered a lot of flexibility for output, but the detail available in the reports could have been greater. The plethora of features (e.g., a variety of quota types, options for specifying quotas) and inherent flexibility (e.g., the ability to create exactly the type of quota you need for a specific environment) that you'll find in competing quota products aren't available here; however, simplicity is sometimes a benefit.

Quota Sentinel
NTP Software is targeting its new Quota Sentinel at the enterprise. (The company still offers its basic Quota Manager product.) Quota Sentinel leverages NTP Software's Enterprise Application Services Extension (EASE) technology for quota administration. EASE is a hierarchical administrative model for distributed configuration management.

I installed Quota Sentinel Release Candidate 1 (RC1) on my Win2K Server system from a CD-ROM that NTP Software provided. At the start of the installation, a message informed me that I needed to install a required application—EASE—before I set up Quota Sentinel. The message asked whether I wanted to install EASE immediately, and I clicked OK. The EASE Setup Wizard installed the EASE service and EASE administrative interface, created an EASE services group, and created a configuration data store. When the EASE setup completed, the NTP Software Installation Wizard for Quota Sentinel launched. The wizard installed Quota Sentinel's administrative and service components, then prompted me to specify an administrative account for the Quota Sentinel service to use when logging on. After the installation completed, the software prompted me to reboot the server.

The EASE Interface
After rebooting, I clicked the Quota Sentinel item under NTP Software EASE in the Start menu. Figure 3 shows the resulting EASE administrative interface. EASE offers a hierarchy-based management platform for Quota Sentinel and other NTP Software applications. The UI's left pane shows your administrative hierarchy and the right pane lists information for the object you select in the left pane. You can model the hierarchy after your organization, and you can apply granular security controls for object maintenance.

To install Quota Sentinel on my NT Server system, I first needed to add that server to the EASE hierarchy. After choosing New Server from the Win2K Server's File menu, I entered the NT server's name and description (e.g., HR Server). A message informed me that the server didn't have EASE installed and asked whether I wanted to install it. I clicked Yes, and after a quick installation the server showed up in the EASE administrative interface. I then right-clicked the new server and chose New, Application, Quota Sentinel from the pop-up menu. The Quota Sentinel Deployment Wizard led me through the remote installation to the NT Server system and gave me the option of automatically performing the necessary server reboot.

Different Terminology
When you begin to set disk-usage limits, you'll discover that Quota Sentinel uses different terminology than the competing products use. NTP Software uses the term template to describe the settings that regulate disk usage.

Quota Sentinel uses User Templates and Object Templates. User templates manage disk space for a given user, and Object Templates regulate disk space that a network object uses. The object can be a share, a partition, or a directory. Quota Sentinel supports individual or combined limits on templates. Combined limits let a number of objects grow unbound until they reach the template limit. At that point, all objects are subject to the actions that you've configured for the template. For example, using a combined limit on a user template would let any user use the entire limit amount as long as all users combined don't exceed that limit. This approach doesn't seem very democratic, but it might make sense in some environments.

You can use server templates to place limits on every root-level directory without individually defining the directories. You apply server templates at a higher level in the EASE hierarchy and let them propagate to subordinate servers. For both User Templates and Object Templates, you can enter a list of extensions for prohibited file types to disallow users from storing certain files on the affected disk object.

Creating and Applying Templates
You create and manage templates in the EASE interface. You can add a Quota Sentinel object to the hierarchy's site level. This Quota Sentinel object doesn't represent a physical installation of Quota Sentinel; rather, it exists so that you can configure properties that subordinate objects will inherit. (Objects inherit properties from upper-level containers.)

To add Quota Sentinel to the Lab site in my hierarchy, I right-clicked the Lab object and selected New, Application, Quota Sentinel. I then created server templates at the site level so that the lower-level servers would inherit their properties. I attempted to use the product's wildcard capabilities for server templates; however, I found that wildcards force you to specify one size limit for every partition. Instead, I created a limit for each partition by entering the drive letter, entering the limit size, and specifying that the limit should be an individual limit. When entering the limit size, your only option is to manually enter the limit in megabytes. You must also manually type in the directory path to which the limit applies.

While I was specifying a path, I encountered a small UI glitch. If I typed the directory path and clicked Apply without first pressing Tab, the software wouldn't save the entry. After I entered the server template, I had to manually refresh the EASE interface to determine whether both subordinate servers had inherited the newly created templates. According to the EASE symbol on each template's icon, I could see that the templates were inherited.

I next configured User Templates for the user home directories and the Files share. I specified the appropriate share and used the domain users group to select users to which the template would apply. I also added the administrators account to a list of users excepted from the template limit.

Thresholds and Actions
You can configure as many as 200 threshold levels and corresponding actions for a template. You add thresholds from the template properties dialog box. When you add a new threshold, the software presents you with a dialog box that includes threshold-configuration options such as threshold level and notifications. Quota Sentinel doesn't support Exchange Server mail; instead, the product requires an SMTP mail server.

I configured threshold options from the site level so that the properties would affect all servers in the site. I set thresholds of 80 percent, 90 percent, and 100 percent and configured each threshold to launch pop-up and email messages to appropriate users and administrators. To make messages more informative and relevant to the recipients, you can insert variables specific to Quota Sentinel (e.g., limit amount, file owner's name, file path). You can also configure an executable or script to launch when an object reaches a threshold.

To deny writing to an object after the object reaches a threshold, you must select the threshold from a drop-down list in the general template settings. (This drop-down list contains a list of the thresholds you've created.) To enact an overdraft, you simply select the Enable Overdraft check box in the general template settings. You specify the duration of the overdraft (i.e., the number of minutes to allow writing) and the amount of disk space you'll allow for post-overdraft write consumption.

Monitoring and Reporting
Quota Sentinel doesn't offer a good tool for monitoring objects to which you've applied templates. You can assign different fonts and colors to various conditions in the EASE display, but the display's lack of flexibility prevents it from being an informative monitoring tool.

The Quota Sentinel Report Module—a separate program included with the software—contains several useful report templates that you can utilize or modify to your needs. The program also lets you create reports from scratch. By selecting items from a static list of available report objects, you can create fairly detailed reports. However, because you can't resize the dialog box that contains the list of objects, the size-limited display window obscures many of the objects' descriptions. Until you actually run the report, you'll have difficulty determining exactly what you're selecting for a report.

More Difficult to Use
Although I could establish usage limits that I wanted for my test environment, I found Quota Sentinel more difficult to use than its competitors. The product's template-creation methods have some limitations that are difficult to work around—particularly when you need to apply templates to multiple servers. Perhaps Quota Sentinel lacks some of the features found in more mature quota-management products simply because it's a new kid on the block. However, NTP Software has built Quota Sentinel on a solid foundation with plenty of room for growth and improvement.

SpaceGuard 4.2
I installed SpaceGuard on the Win2K Server system from a CD-ROM that the company supplied. The installation program prompted me for licensing information and an installation directory. For the SpaceGuard service logon, I specified an account that I created for that purpose. I also specified that the account should be a member of the local administrators group. The software then prompted me to enter the name of a configured Messaging API (MAPI) profile to use for email notifications. (You can use MAPI or SMTP for email notifications.) The entire installation took about 2 minutes.

After the installation program finished copying files to the server, the SpaceGuard Client Setup program launched and prompted me for a directory path to which to install client files.

Setuprem.exe is a command-line utility you use to install SpaceGuard on remote servers. The program requires that you use arguments to supply all the setup parameters—the result is a long, cumbersome command string. After I executed the command with the appropriate arguments, the system installed SpaceGuard Server on the remote NT Server system and the service started automatically.

The SpaceGuard Client
To launch the SpaceGuard Client, I clicked the SpaceGuard icon on the Start menu. The client UI, which Figure 4 shows, isn't as complex as other quota products' UIs. From the File menu, you can choose Monitor, Configure, or Overview. The monitor window shows quota information for an individual server. You can open multiple monitor windows to view quotas on different servers. You use the configuration window to add and manage quotas. The overview window shows summary information for multiple SpaceGuard servers. From the overview window, you can launch the monitor window for a specified server.

You can customize all three windows' views to display relevant information. After you configure the SpaceGuard Client to your liking, you can save the desktop for future use. Choosing Service Options from the Tools menu opens the SpaceGuard service configuration program, which you use to change general configuration items, alter SpaceGuard Client window-refresh rates, and modify notification messages.

Quota Types
SpaceGuard offers only standard and auto-add quotas. Both types of quotas apply to directories, but the auto-add quota configures itself for all existing and newly created subdirectories. An obvious limitation of SpaceGuard's few quota options is the inability to manage usage by user for any shares available to multiple users.

Adding and Managing Quotas
In the configuration window, you can add or alter quotas. When you first open the configuration window, the Microsoft Windows Network is the only displayed item. You must navigate to the servers on which you've installed SpaceGuard and right-click the object to which you want to apply a quota. Then, choose Add Quota from the pop-up menu to access the Quota Configuration dialog box. The dialog box has four tabs: Specification, User Actions, Administrator Actions, and Detection.

On the Specification tab, you configure the quota's warning limit and maximum limit. Also on this tab, you can select the Include subdirectories check box to ensure that files stored in subdirectories count toward the quota. The Detection tab lets you choose the method for monitoring changes on disk objects. The two available methods are Automatic on changes, with a user-specified delay in seconds, or Every interval, with a user-specified interval in minutes.

I configured quotas for each partition on both of my servers: I entered a warning limit and a maximum limit in megabytes, then chose Automatic on changes with a delay of 5 seconds. In the other products, which support user-based quotas, I gave each user 50MB. Because I couldn't create user-based quotas in SpaceGuard, I used a standard quota for the Files share and multiplied the number of users by 50MB to equal the same total disk consumption.

To create an auto-add quota on the user home directories, I selected the E:users directory and chose Auto add from the Quota menu. (The Auto add Quota Configuration dialog box looks like the standard Quota Configuration dialog box, but after I finished my configuration, I verified in the monitor window that the software had set a quota on each user's home directory.)

Thresholds and Actions
On the Quota Configuration dialog box's User actions and Administrator actions tabs, you can configure actions based on the product's two threshold levels (i.e., the warning limit and the maximum limit). You can choose to display a popup message, send an email message, revoke user-write access, or execute a command. You can configure both the warning limit and the maximum limit to trigger any combination of the actions—with the exception of revoking user-write access, which you can set only for maximum-limit violations. You can specify only one user for access revocation, so this action works well only for a user home directory scenario. The pop-up and email messages are predefined, but you can use the SpaceGuard service configuration program to modify them.

Monitoring and Reporting
You monitor quotas from each SpaceGuard server's monitor window. Figure 4 shows monitor windows labeled PRODUCTION and CORP. To modify a monitor window's contents so that it displays relevant data, right-click the header and choose Configure Column. From the resulting drop-down list, you can choose from a large selection of counters.

You can also provide users with a utility called Quota Query Tool, which gives them a way to monitor quota information as it affects them. SpaceGuard doesn't offer tools for creating reports.

Perhaps Too Simple
SpaceGuard is extremely easy to use. Unfortunately, the product's ease-of-use is due largely to its lack of functionality. If you need only to implement quotas on users' home directories, SpaceGuard might be a good choice. But if you need user-based quotas or reporting features, you'll need to look elsewhere.