How to request restoration of lost disk files on pangea

Last revision July 15, 2004

There is no such thing as "undo" on a Unix system. Once you remove a file, it is gone and cannot be restored directly from the disk. The only alternative is to restore it from some backup medium.

Each early morning about 3 a.m., from Tuesday through Saturday, the /home, /play, /aufs, /WWW, /ftp, /var/spool/mail (email inboxes), and system disk directories on pangea are backed up to magnetic tape. The /scr1 and /scr2 directories are not backed up! These backup tapes are kept for five weeks and then recycled. Archive backups that are kept for many years are also done once per year, usually in late summer or during the winter break. The primary purpose of these backups is to protect us against disk hardware failure. It is also possible to recover individual files or directories that have been accidentally removed by the user.

To request restoration of lost disk files, send an email message to the special address backup@pangea.stanford.edu. Provide all the following items of information:

1. Exact names and directories of the lost files. You can specify groups of files, such as "all the files in my home directory whose names begin with data". You can also specify entire directories, such as "the subdirectory programs in my home directory".
2. The date when you accidentally removed the files from disk, or if you cannot recall that, the date when you first noticed that they were missing.
3. The date when the files were last modified. Because of space constraints, most backup tapes only record the files that were changed since the last full backup, which is generally done only once per week. Therefore, in order to locate the tape that contains your files, it is important to know when they were last changed or created. If you cannot recall an exact day, give an approximate answer, such as "changed this week" or "not changed for at least two weeks".
4. If you are asking for restoration of your email INBOX, please include what program you use to read email, for example, pine, Eudora, etc. This makes a difference in how the file is restored.

Restoration of these files is done on a time-available basis. It will usually take several days before they can be restored. You will receive an email when the files have been restored. In order to prevent accidental disruption of your other files and directories, recovered files are always written into the /scr1 disk. You must copy them back to your own directory within 15 days. We will restore email inboxes to their correct location for you. The system automatically erases all files more than 15 days old left in /scr1. Also, if you have applied special permissions to these files (such as no world read permission), you must reapply those permissions after copying them back to your directory.

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