Using Quota Management to Safeguard Windows NT Network Availability and Performance

- by Steven Toole

Before the first drop of hurricane rain could hit the beaches, the Windows NT file servers began crashing at the County of Miami’s office in Dade, Florida. It wasn’t the hurricane’s high winds, flooding, or power outages that caused these failures. It was the County’s employees. 
Fearing the worst for their desktops after being hit by a hurricane three years in a row, employees developed the habit of copying their desktop’s hard drives onto the servers as soon as news about a new hurricane hit the airwaves. Dozens of employees with desktops averaging four G-bytes to eight G-bytes started to copy their desktop data simultaneously to the servers. The servers couldn’t take the pounding.
Not every information technology (IT) organization has hurricane warnings to worry about. On the other hand, every Windows NT/2000 server systems administrator needs to ensure server availability and performance. Specifically, they need to be concerned about uncontrolled server disk capacity consumption by employees. 
Strategic Research Corporation, a storage research firm in Santa Barbara, California, estimates that the majority of unplanned outages in distributed Windows NT networks cause about 55 percent of all disk drive failures. This percentage also includes failures by servers that have exceeded their capacity. Strategic Research Corporation also estimates that disk space consumption in some organizations has reached rates from 70 percent to 100 percent annually. To this end, overloaded capacity can make a server’s performance suffer. 

Short of a complete server crash, any employee can seriously compromise server performance and application availability by excessively storing large files onto servers shared by other employees. Some systems administrators deal with this problem by manually babysitting a server’s capacity level or using load balancing to control the amount of data on a server. Better still, a systems administrator should consider setting multiple, real-time directory disk quota thresholds on the amount of space assigned to each employee and to each department. Employees should receive automatic alert notifications as they get close to their quota thresholds. This procedure allows systems administrators to allocate storage evenly as a shared resource, and to make sure the types of documents saved conform to the IT’s department policy for what belongs on the server. 

Use Soft Quotas to Monitor Server Disk Usage Transparently 
Directory quotas enable systems administrators very easily to maintain server performance and to avoid system crashes that may otherwise occur due to capacity levels that have been exceeded. Soft quotas enable employees who’ve exceeded their quota threshold to continue to save files on the server. Systems administrators can automatically execute command lines, set alerts to trigger, automatically run reports, or send the activity to the event log. 
Soft quotas provide a good way to monitor the status of any server’s disk usage as compared to the server’s disk capacity. Soft quota alerts can provide plenty of fair warning when a server is about to reach its allowable capacity. In fact, soft quotas are useful for monitoring server disk usage at the 50 percent to 85 percent range. 
On the other hand, soft quotas can work only if the IT department can educate and empower employees about the importance of grooming their disk space following a quota threshold alert. Otherwise, the IT department has limited control over employee’s storage usage.

Enforce Hard Quotas to Ensure  Maximum Server Uptime
Unlike soft quotas, hard quotas allow the server to refuse any additional I/O event, such as saving a file after the quota threshold has been met or exceeded. To this end, hard quotas can ensure a certain percentage of free space for server performance, application availability, and continuity. 
A systems administrator can set hard quotas in a variety of expressions, including percentage of available space, such as 89 percent; fixed quantity, such as 10 Gbytes; or percentage of space currently used, such as 150 percent of current space used. These expressions provide systems administrators with the flexibility of setting the appropriate hard quotas for the particular device and the nature of the data stored on each server.
In addition to setting directory-level hard quotas, systems administrators can set a hard quota on each employee’s space within the directory quotas on some servers. This practice can prevent employees from jeopardizing server performance. If the sum of each employee’s individual quota totals less than the overall directory quota, the server will still be under its total allowable capacity, and the performance will be maintained. These conditions will hold true even if each user reaches his or her maximum quota simultaneously. 
Setting hard quotas puts the burden on the IT department to make sure employees understand that they have to free up space before they can store additional documents. Thus, the IT department needs to put a good communications program in place before turning on hard quotas and to find ways to make it easy for employees to groom their space. A hard quota with an overdraft allotment enables employees who’ve exceeded their quota to save their files without any disruptions to their work. As employees get alerts, the IT department can e-mail them a report listing all of their files. For example, a HTML page with file links allows an employee to click on a file extension, view the file, and then click on link again to delete the file. 

Windows 2000’s User Quotas Don’t Hold Up
Windows 2000 includes a native user quota management capability. However, with only one quota threshold, employees don’t get any warning before reaching their quota limitation. Lack of warning can prompt unpleasant calls from employees to the systems administrator or help desk. In addition, Windows 2000’s user quotas don’t allow employees to complete saving a file if they’ve reached or exceeded the quota during the save. This procedure can prove disruptive to employees. Windows 2000 server does not include directory quotas, nor does it allow any quota control beyond the user level.

Third-Party Software to the Rescue
Third-party quota management software companies offer better alternatives than Windows 2000’s quota management native capability. Some products include multiple quota thresholds so employees have plenty of advanced warnings when they approach their hard quota. Other useful capabilities include providing employees with reports listing their files or enabling a blocking mechanism to keep specific files types, such as mp3’s, from being stored on the network.
On the surface, quota management products may appear to offer similar functions. However, the scanning technology a quota management product greatly distinguishes one product from another. For example, real-time quota management products don’t do periodic scans, and thus don’t affect a server’s performance. However, a quota management product that scans every five or 10 minutes can put a dent in a server’s performance. This type of product may also cause employees to exceed their quota because the scan cycle happened after this event. 

IT Can Make All the Difference
Successful overall management of disk storage also has to go beyond disk quota management to include the following factors: 
-How well the IT department can get employees, especially top management, to understand the reason for allocating and monitoring storage as a shared resource, 
-How carefully the IT department listens to needs of employees and provides them with tools, such as CD ROM burners, and techniques, such as HTML-based reports, to manage their space effortlessly, 
-And how strategically the IT department uses quota management data to make storage decisions, such as the need for retention policies for moving files to secondary online storage.

To this end, if everyone in the organization masters his or her role, then servers can become top performers.

Steven Toole is the Vice-President of Marketing at W Quinn Associates, Inc., Reston, VA, which markets storage resource management software for Windows NT. Toole has held marketing positions at Axent Technologies, a marketer of security software.

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