DCIT LAN Systems

Personal Disk Quotas

- Draft Version -

At Clemson, we have over 36,000 users defined to the Local Area Network (LAN). We are one of the few universities that provide personal storage to every user. Most are planning to offer it in some form, but have not yet worked out the logistics of automating both userid management and the location of the storage on a user-by-user basis. The reasons for providing the storage are obvious, but the management can be a problem if certain rules are not put into place.

We started providing personal storage for all students in August of 1995 and all faculty and staff in January of 1996. As you probably know, our LAN is based on Novell Netware and Microsoft Windows NT Server with Novell Directory Services (NDS) being the glue that holds together close to 100 servers. When you login to the network, you unknowingly attach to several of these servers simultaneously. Of these 100 servers, there are 5 basic types. This document will focus on quotas on the Personal Data Servers, but it is important to understand that the other types exist.

There are currently two of these. They are named STUDENTD and EMPLOYED. The STUDENTD server holds the home directories (personal storage) for close to 25,000 named student user accounts. The EMPLOYED server holds the home directories for about 11,000 named faculty, staff, and miscellaneous accounts. On both servers, users can create personal web pages.

There are many of these. They hold collaborative data and applications for faculty and staff in colleges, departments, and/or workgroups. A group can also make use of this collaborative storage space to serve web pages to the Internet without having to run a web server locally. A faculty member may use these servers to do collaborative work with students in a class as well as accept secure file submissions from students.

There are also many of these. They support the public and departmental labs by serving up general purpose and teaching applications to workstations in the labs.

There are three of these servers. They operate in the background, keeping the network running smoothly by synchronizing between themselves information about users and resources on the network and the security associated with them.

STUDENTD currently has over 90 gigabytes of storage dedicated to holding user home directories. EMPLOYED has over 50 gigabytes of storage for faculty and staff home directories. Quotas are limits defined to a directory that limit the cumulative size of all files in that directory (and in subdirectories under it). If quotas were not implemented, in a matter of days a few users would use all of the storage we have on line on these servers. Currently, at account creation student home directories have a quota of 20 megabytes while faculty staff home directories have a quota of 100 megabytes. This may not seem like very much storage (and in today’s computing environment it is not), but the fact is that most users that store things in their home directories are far below their limits.

Actually, we are grossly over committed on personal disk storage even with these quotas. If you multiply 20 megabytes by 25,000 users, you end up with a disk requirement of approximately 500 gigabytes on STUDENTD instead of the 93 gigabytes mounted there. We are banking on the fact that not all users will want to use their allocation. This is a safe bet since there are about 17,000 regular users of STUDENTD, but most only use a small fraction of their storage. On EMPLOYED we are hedging our bets even further as 11,000 users times 100 megabytes produces a disk requirement of approximately 1100 gigabytes. For those playing at home, that’s 1.1 terabytes of storage.

We have heard from users who assume that we have this much storage online and should be willing to blindly approve large quota increases based on the fact that not everyone will use theirs. We already assume that and are in fact counting on it. Our quota increase policies have this in mind.

Many faculty/staff users are unaware of the existence of their group server. All users have access to at least one. For the most part, there are no disk quotas in effect on these servers. The servers are positioned closely on the network to the users that are using them for improved performance. If you have data that is considered department or workgroup data, please store it on the group server and not in your private home directory.

Only data that is private to you as an individual should be stored in your home directory. STUDENTD and EMPLOYED are backed up nightly so your home directory is a good place to store personal data that needs to be recoverable in the event of human error, computer error, or natural disaster. E-mail is a good example of information that you might want to keep in your home directory. Your home directory is a good place to keep data that needs to be secured more so than your local hard disk affords. You are the only person that has rights to that file space unless you permit others. You should not store data here that is not vital to your mission as an employee or student at Clemson University.

Do your best to keep your disk space clean. Delete files that you don't need anymore. Delete "temporary" files that seem to accumulate in all situations. Most importantly, delete old mail messages and more importantly file attachments to mail messages that you have moved somewhere else. If you are using Eudora, set the option to automatically empty your trash at the end of each Eudora session. Don’t use your mailbox as a filing cabinet.

We chose the current baseline quotas based on the needs of the average user. Of course there are users out there whose needs are beyond those of most. As mentioned above, we try our very best to approve all requests based on legitimate need. There are a number of factors involved in approving additional space requests. One is the amount of free space currently available on the server. We usually do not try to add disk to these servers during a semester. If disk space is getting tight, we may not be able to grant a request. DCIT is not in the business of policing content of files. However, if a request is submitted for additional disk space, and the space you are using is being used in a manner questionable to your mission here at the University, there may be a problem approving the request. Requests for large amounts of space are a problem on these servers. In most cases, these requests are made to store data that is group oriented in nature. However there can be exceptions and we will do our best to work with you in these situations.

As we are over committed on personal disk storage, we are constantly monitoring the amount of free space on these servers. New disk subsystems are being added to these servers at a frequent rate. DCIT exists to serve the computing community at Clemson. We would love nothing better than to remove quotas altogether and add disk by the truckload. However, we are limited in what we can provide based on our budget. We really try to approve all the requests that we can, within reason, for storage space. Hopefully, this effort will be realized by users, avoiding the perception that the computer center isn’t trying to help them. If you have questions concerning this document or the policies outlining personal disk storage, please contact David Condrey, LAN Systems Manager, via email at davidc@clemson.edu..