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Quota Server is a software solution designed
to monitor disk-space usage and prevent over-utilization of storage. The
administrator defines how large certain disk objects are allowed to
grow, and Quota Server will monitor these objects and enforce any
administrative set limits.
In Quota Server, the monitoring and enforcing of disk Quotas can be done
in two different ways by using two different core engines. You can use
just one of these engines, or a combination of both. The administrators
can make the decision on which engine best suits their network
environment. When a Quota is defined, you select the “Quota Type”. The
type of Quota will decide the engine which will be invoked and used to
monitor the disk object in question.
If the type of Quota
is “User Quota”, the engine used will be the Interception Engine. The
Interception Engine is a device driver process, much like a driver for a
graphics card or a mouse. The Interception Engine intercepts I/O packets
going to and from the file system. The Interception Engine determines
the user account that generates the I/O packet, which could be the
saving of a file for example, and then it calculates whether the amount
of data saved is within the disk Quota limit for the user. If it is, the
device driver will let the save operation pass through and the save
operation will be completed. If the save operation would take the user
account above the Quota limit, or threshold, the Interception Engine
will deny the I/O operation, thus hindering the process from being
completed.
A User Quota takes
the actual user into account when accounting disk Quotas. For example,
you can apply a disk Quota of 50Mb to user DOMAIN\Joe. And another disk
Quota of 40Mb to user DOMAIN\Jean.
If the type of Quota
is “Object Quota”, the engine will be a regular NT service. The service
will be notified by the file system, whenever there is a change to a
disk object with a Quota. Upon that file change, Quota Server will size
up the disk object to determine whether the object is above its Quota.
If it is, Quota Server will adjust the security Permissions for that
disk object so that no user can enlarge the data that is stored in that
disk object. Users will still be able to delete files and data, as well
as open and execute programs and documents. Only writing and enlarging
files is prohibited by the NT security permissions applied by Quota
Server. The actual enforcement of these permissions is handled by the
operating system itself.
An Object Quota does
not take into account which user actually fills up the disk object in
question. The Quota is simply applied to the entire disk object. For
example, if an Object Quota of 50Mb is applied to D:\Users\John, it does
not matter if user JOE fills up the JOHN directory. When the object
reaches 50Mb, Quota Server will block that object from growing larger.
This type of Quota is recommended for common group directories, home
directories, common fax areas, etc.
Interoperability
In mixed enterprise
environments, there is often a need of integrating Quota Server with
other management systems. This can be achieved in different ways. This
page is intended to give some information on available options.
Using the Quota Server COM API:
The COM API [Application Programming Interface] exposes a library of
function-calls that can be used for accessing Quota parameters.
Everything that can be achieved through the regular Quota Server Client
GUI can also be achieved through the COM API. The API can be used from
Visual Basic, Visual C++, Microsoft Excel and other similar packages.
Using the command-line tools:
A set of easy-to-use command-line tools are available in the Tools
sub-directory of the Quota Server installation directory. There are
tools that can export Quotas, import Quotas, report on Quota usage,
delete Quotas, and set individual Quotas.
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Integration between the
Human Resource module in SAP R3 was done through the COM API
from Visual Basic. Whenever a new employee arrived, the Human
Resource module would create a Windows NT account, a
home-directory and assign an associated disk Quota.
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A replacement of the
Quota Server GUI was achieved by another customer that wanted a
couple of custom screens to look at. By using Microsoft Excel
and the built-in Visual Basic for Applications, they created a
custom Quota Server management station within Excel.
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A global computer
company, created a SNMP integration with their existing
Hewlett-Packard OpenView system, by reading the Performance
Monitor counters. That provided them with statuses such as
Number of Locked Quotas on a server, etc. They were also able to
generate warning thresholds in OpenView based on the Quota
Server parameters.
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