There is only limited on-line disk storage space on the Math department systems for user file storage. In order to ensure that this limited resource is shared fairly, and to prevent disk space from being filled up, the following policy has been adopted by the Departmental Computing Committee. Please note that the allocations stated below are not meant to be the actual share for all users, because even if a quarter of all users reach their limits, the system will run out of all disk space available. We appreciate your effort in conserving disk usage.
Standard UNIX disk allocationsThe disk quota system allocates a soft block limit which you can bypass for 7 days, and a hard block limit which can not be bypassed. You may use disk blocks above your soft limit for only 7 days, after which you may not write to the disk anymore. During the login process, the system will warn you if you are above your allotted quota. Please treat this message seriously, since failure to relinquish disk space may cause damage to your existing files or prevent you from writing to the system disk.
Standard NT disk allocationsSince the NT operating system is relatively new to the Math department, a disk space policy has yet to be established. In lieu of such a policy, we ask that you not store large amounts of data in your Z: home directory.
Special allocations in individual cases
Requests for more disk space should go to the Chair of the Departmental Computing Committee (DCC), whose e-mail address is chairdcc. (In the case of redwood and joshua, requests will be referred to the Applied Math group for final decision.)
Backup services provided by the system staffTo protect against catastrophic failures, such as a fire or a disc drive becoming mechanically inoperative, all UNIX and NT servers, as well as desktop UNIX machines, have their files backed up to tape on a regular basis.
Once a week, the entire contents of the disks on these machines are backed up to tape in their entirety. In addition, incremental backups (where only files which have changed from the last full backup) of all eligible machines are performed each weeknight. No backups are made on weekends or holidays.
These backup tapes are retained for two weeks, and then overwritten.
In addition to the weekly backup schedule, a full backup of all UNIX machines and the NT servers is made at the end of every academic quarter. These End-Of-Quarter (EOQ) tapes are retained for one year.
The primary reason that we make backups is so that we can recover from a disaster (disk crash, earthquake, fire, etc.) if we have to. Since these sorts of events are infrequent, the backup procedures are optimized for daily backups, and not for occasional data recovery. After all, we do backups every day, but if we're lucky, we'll never have a disaster.
Since the backup strategy is not oriented towards data recovery, retrieving files and data from our backup tapes is a time consuming and tedious task. As such, requests from individual users are a low priority. If you accidently delete a file, it may take several days until someone can process your request. As such, your safest course of action is to make copies of your important files and store them on floppy, ZIP or JAZ disks.
It is important to note that desktop NT machines are NOT backed up by the system staff. These machines frequently are too large to backup over the network, and require more backup resources than the department can provide.
If you have data on your PC which you MUST have backed up, you should put it on your Z: drive (networked home directory). You are free to put any data you want on your other drives, but it will not be backed up.
If a PC machine suffers a catastrophic disk failure, the machine will need to be rebuilt from scratch (a fresh install).
Suggestions for Saving Disk Space on UNIX Systems
To monitor disk space (assuming your home directory is the current directory):
quota <login-ID> shows your disk quota and usage information
(where <login-ID> should be replaced by your login-ID).du -a ~ shows how much space each of your files use (in kbytes) du -s * shows how much space each subdirectory use (in kbytes) When compiling/linking using cc or f77, use the "-s" option to reduce the size of the resulting executable. This option will strip the symbol information in the executable; you won't need this information unless you plan on running a debugger.
If you have ".o" object files lying around, they're good candidates for deletion; you can always recompile and create them again.
Delete "core" files produced when your program crashes as soon as you have finished debugging them with dbx or adb.
Don't keep the source code for program packages on-line unless it's really useful. You can restore it from the distribution media whenever you need it.
Avoid keeping large data files. Frequently they aren't that expensive to recompute, and you tend to forget what is in them unless you keep careful records. If you must keep large files on line, consider compressing them with the "compress" or "gzip" commands.
The saved state of some games takes 250,000 bytes. When resources are tight, the first suggestion made is to forbid games. Be responsible, and encourage fellow game players to be responsible, lest your recreation be turned off.
Avoid saving news articles and mail unless it is really important. Shorten saved articles by editing. Don't leave old mail in your mailbox file; delete it promptly.
Suggestions for Saving Disk Space on NT Systems
If you have data which is not essential, you can store it on your local machine. It won't get backed up, but you'll be able to use your entire disk as you like (filling up the C: disk, however, may cause NT to have problems; avoid this).
Don't keep the source code for program packages on-line unless it's really useful. You can restore it from the distribution media whenever you need it.
Don't install software to your Z: directory. Install it on C: or D: instead.
Last Updated: 9/30/98 by es