ITS Documentation

AFS Overview

R1070 • December 2013
Table of Contents


What Is AFS?

Just as Information and Technology Services' (ITS) e-mail service lets you access your e-mail from different computers at different locations, the Andrew File System (AFS) lets you access your documents and files from different computers at different locations. AFS is a central file storage, sharing, and retrieval system that you can access from Mac, Windows, and Unix computers.

Home Directory

Personal storage space on AFS is called your "home directory." Students who are listed by their department as "Active in Program" and all faculty and regular staff on the Ann Arbor campus are eligible to receive an AFS home directory as part of their standard computing services. Students affiliated with the College of Engineering are automatically provisioned with AFS home directories. Other students may choose to use the AFS Self-Provisioning Tool to receive a 10GB AFS home directory or to verify they already have one. You receive a quota of storage space in your AFS home directory. Your AFS home directory is created with some generic folders for your use. You get the following folders:

  • Public. Any AFS user in the world can see that you have a Public folder inside your AFS home directory and can read the documents inside it. No one other than you, however, can make changes to, add, or delete documents.

  • Shared. Any U-M AFS user can see that you have a Shared folder inside your AFS home directory. No one other than you, however, can make changes to, add, or delete documents.

  • Private. Any AFS user can see that you have a Private folder inside your AFS home directory. If they open that folder from a Macintosh computer or a PC and look inside, they will see the names of folders, but will not be able to see the contents. No one other than you can make changes to, add, or delete documents.

  • Network Trash Folder. This folder is for Macintosh system use only.

If you use Pine for e-mail or trn for Usenet news, other folders (for example, mail and news) may be created for you when you use those programs. It's best to just leave these folders alone; they are for the use of those programs only.

What You Can Do With AFS

AFS is essentially a file storage medium; it gives you a central, convenient place to store files and documents. Here's what you can do with your AFS space:

  • Web publishing. You can publish your own home page on the web by using the Public folder inside your home directory. Create a folder called html inside your Public folder, and put your web page inside. For more detail, see thePublishing Your Web Site Using Your Home Directory section of Using MFile To Access Your IFS Home Directory Over the Web (S4311).

  • File storage and access from multiple locations. You can access files in your AFS home directory from any computer with an Internet connection and the appropriate software installed (see Connecting to AFS for several connection methods.) This means you don't need to carry flash drives or other storage media around with you.

You don't have to worry about files on flash drives being damaged or lost, either. A benefit of AFS is that the files are backed up regularly for you. (See Backups of Your Files in AFS for details.)

  • File sharing. You can put files in your AFS home directory, or in other directories on AFS, for others to share. This is a good alternative to sending e-mail attachments, particularly when several people need access to the same file. AFS can serve as a shared work space for a group of people.

Connecting to AFS

NOTE: Depending on how you connect to AFS, you may see a number of files with names that begin with a period or dot. You can just ignore these files. They are created by the system and are required for use of some ITS computing services.

From the Web

The easiest way to get to your AFS home directory is to use MFile on the web. MFile is at this URL: http://mfile.umich.edu/

See Using MFile to Access Your AFS Home Directory Over the Web (S4311) for instructions.

Windows

ITS recommends that you install the Windows Internet Access Kit (WIAK). It installs an ITS Home Directory (sftp) shortcut; in the U-M Internet Access Kit folder on your desktop. This shortcut opens a connection to your home directory using WinSCP. For details about using WinSCP to copy files to and from your home directory, see Use WinSCP to Transfer Files with sftp [Windows] (S4387). (If you do not use the shortcut, use SSH to connect to the hostname sftp.itd.umich.edu.)

Mac

ITS recommends that you install the Mac Internet Access Kit (MIAK). It includes Fugu for Mac OS X (also available free from http://rsug.itd.umich.edu/software/fugu/). Fugu is an SFTP (Secure File Transfer Protocol) program that allows you to copy files to and from your home directory.

Fugu has built-in Help. From the Help menu, select Fugu README. To connect to your AFS home directory with Fugu, use sftp.itd.umich.edu as the host name and your uniqname as the user name.

Group Directories

You can arrange to have a group AFS directory—to use as a shared work space, as a means of publishing on the Web, or for some other purpose—for your department, unit, or student organization. Also, faculty members can have an AFS group directory for a class that they teach.

Navigating AFS

Like most file systems, it is organized by directories. At the AFS root level directory, you can connect to implementations of AFS worldwide. The first layer of directories in the AFS file space contains what are called cells. A cell is an administrative domain and is generally controlled by a company, university, department, or other large group of users. ITS manages the umich.edu cell for the use of the U-M community. There are other cells on campus. For example, the College of Engineering manages the engin.umich.edu cell.

Within the umich.edu cell are five directories: class, group, system, um, and user.

diagram of afs showing the umich.edu cell

Within the user directory, there are 26 folders, one for each letter of the alphabet. Within each of those folders are 26 folders, again one for each letter of the alphabet. Individual user home directories are inside, filed by the first two letters of the person's uniqname. For example, to find the home directory of someone whose uniqname is bjensen, you would go to the user directory, then open the b directory, then the j directory.

People generally talk about locations in AFS in terms of pathnames. A pathname is basically the path one takes (or the path your computer takes) to get to the directory or folder you want. For example, the pathname to bjensen's home directory would be /afs/umich.edu/user/b/j/bjensen.

Backups of Your Files in AFS

All the files on AFS are backed up regularly for your security and convenience.

  • Daily backups. Daily backups are kept for 14 days.

  • Weekly backups. Weekly backups are kept for eight weeks.

Should you accidentally delete, change, or otherwise destroy files in your AFS home directory, you can get copies of your space restored from the backups. You can access the most recent daily backup yourself; AFS staff members can restore the older backups for you. For details, see AFS File Backup and Restore (S4110).

Controlling Access to Your Files

Inside your home directory are some folders with pre-set permissions. Your Private folder, for example, is set so that no one but you can see and make changes to documents and files inside it. You also have a Shared folder and a Public folder. Note that others cannot see files placed directly in your home directory, so it's best to use the folders provided for you if you want to share files. You may find the preset folders meet your needs. If you wish, though, you can set permissions yourself.

From the Web

You can use MFile on the web to set and change permissions on your AFS folders. See the Setting Folder Permissions section of Using MFile To Access Your AFS Home Directory Over the Web (S4311).

Using Unix

You can control whether other people can see the files and documents in the folders inside your AFS home directory, whether they can make changes to them, and more through the use of Access Control Lists (ACLs). An ACL is a list of uniqnames and/or protection groups to which access rights have been assigned. (A protection group -- or pts group -- is similar to an e-mail group except that it is a list of uniqnames rather than a list of e-mail addresses; it is used to assign permissions to a group of people.) ACLs are set for folders.

For example, you might create a folder in your AFS home directory that you want to use for a group project. You could then set ACLs for that folder to allow only your group members to see what is inside it and make changes. For how to set and change ACLs, see Using Access Control Lists (ACLs) With AFS Directories and Folders (S4111).

If you find yourself needing to set ACLs on a folder to more than three or four people, consider using a pts group. This can be especially helpful if members of the group to which you want to grant access changes over time. See Creating and Administering Protection (pts) Groups (S4033) for how to create and manage pts groups.

Additional Resources

Visit ITS's Information System to obtain ITS computer documentation and other resources. A list of relevant documents follows:

The ITS Service Center provides a variety of computing help resources.

For further help with this or any other topic, call 734-764-HELP [4357] or submit an online service request.

Appendix: File Sharing Tips

When you share files with others, it helps to keep in mind what platform (that is, Mac or Windows) and what software they use. You may need to save files differently in order to share them with others.

Windows and Mac

Windows and Mac computers save files in different formats. If, for example, you use Windows and the person you want to share a file with uses a Mac, you may need to save your document in a format readable by Mac computers -- or vice versa -- before copying it to your AFS space. Microsoft Word, for example, offers a variety of formats in the Save and Save As dialog boxes. Select the appropriate one from the Save File Type drop-down list.

Software Version

Older versions of software generally cannot open documents created by newer versions of that software. If you use a newer version of Microsoft Word, for example, and the person with whom you want to share a file uses an older version, you should save your document in the version of Word that person uses (select it in the Save As dialog box) before copying it to AFS.

Filename Extensions

If you share files with Windows users, you may want to use DOS-type filenames even if you work on a Mac. The extension part of the file name -- a dot followed by an abbreviation -- indicates the type of file. Here are just a few samples of filename extensions:

Extension Type of Document
.doc Microsoft Word documents
.wp WordPerfect documents
.xlt or .xls Microsoft Excel documents

.ppt or .pps

Microsoft PowerPoint presentations
.pdf Portable Document Format
.htm or .html HTML files
.jpg JPEG graphic files
.gif GIF graphic files
.txt text-only files
.rtf Rich Text Format
.exe an executable file for Windows
.sea Self Extracting Archive