Evaluating Spaceguard for NT in a cluster environment.

Ing. Bart Teunis

Abstract:

 

While using Spaceguard in normal, non-clustered environment we were very curious about how this product will perform in a cluster-environment. I installed Spaceguard in a cluster-environment and tested the functionality in this cluster. The main conclusion must be that the tool works perfectly in a non-clustered environment but has several lacks in a clustered environment. There is a free trial version available at www.tools4nt.com.

While using Spaceguard in normal, non-clustered environment we were very curious about how this product will perform in a cluster-environment.

I installed Spaceguard in a cluster-environment and tested the functionality in this cluster. The main conclusion must be that the tool works perfectly in a non-clustered environment but has several lacks in a clustered environment. There is a free trial version available at www.tools4nt.com.

 

About the product:

 

Spaceguard is developed by Simac software services and is based on the similar version for Banyan Vines.

The tool is very easy to install and easy to manage. It's functionality is based on the fact that the user-rights were cut down when the user exceeds the limit on the hard-disk. The user is able to write data on the disk again when he or she cleans the directory where the limit is set on.

 

The installation:

 

The installation in a non cluster environment is pretty straight forward. In a clustered environment there several things different. The Tools4NT web site offers good help in this case. The things that are different are:

 

-         Spaceguard must be installed on both nodes, so there must be two licenses

-         There is a registry that must be replicaded (HKEY_LOCAL_MACHINE\SOFTWARE\Simac Software Service\Spaceguard

 

Further Spaceguard must be installed as a generic service on the virtual server. This service belongs to the same group as the file share resources and the disk resource. The service is dependent from the disk resource, IP resource and the network name.

 

Following the instructions given in the manual and on the web site installing Spaceguard wasn't very hard.

 

Testing the functionality:

 

In a cluster environment we set the limit of space which a user could use to 100 MB.

In the first step we tried to copy 90 MB of data to this directory. This was possible. Next we tried to copy a additional 20 MB of data which was not possible. This worked fine. We cleaned the directory and tried to copy 200 MB of data which was not possible due to the limit set. Our conclusion was that the functionality was good.

 

In the next step we cleaned the directory and copied 90 MB of data and performed a fail-over. The service was taken over by the other node. We tried to copy the additional 20 MB of data, which was possible. This was not what we liked to the product to do. Next we performed a fail-back and tried to copy another 20 MB of data, which was not possible.

Next we cleaned the directory and performed a fail-over. We tried to copy 200 MB of data into the directory and it was possible. After the fail-back we tried to copy again the additional 20 MB and this was not possible.

 

Conclusion:

 

We evaluated Spaceguard for NT in a cluster environment. Although Spaceguard should be cluster-aware we came to the following conclusion: Spaceguard, indeed is cluster aware, the service kept on running by a fail-over and a fail-back, but lacks in functionality by a fail-over. Because after the fail-back it was not possible to exceed the limit we concluded that the functionality returns by a fail-back. Therefore we think that Spaceguard is a very good product in a non-clustered environment, but using Spaceguard in a clustered-environment can have some risks concerning space-quota.

 

Remarks from Simac software products :

 

Microsoft clustering can be implemented in several ways:

1. Active/ passive; Node A is active, Node B is passive. After Node A crashes, Node B will become the active node. SpaceGuard can support this type of clustering without any problems.

2. Active/ active; Node A owns the file service, Node B owns another process, like Exchange or SQL server. After Node A crashes, Node B will become the owner of the file service. SpaceGuard can support this cluster type without any problems.

3. Active/ active; both Node A and B own a (separate) file service. After Node A crashes, Node B will become the owner of Node A's file service. In the current version, the SpaceGuard service on node B is not able to check the quotas of node A after a failover. It will only guard the quotas of node B.

 

Simac will create a new SpaceGuard release, which is able to handle this type of clustering as well. This new release will be available November 1999.

 

Acknowledgements:

 

We like to thank Daniel Huisman (Simac Software Products) for his comments on this article.