X-Git-Url: https://sipb.mit.edu/gitweb.cgi/wiki.git/blobdiff_plain/36d5a3eeb8499fabd3ee04b476330bef4cf937f0..04ffeb2bb0b6b6bf48060f2f20c508d2b01aa16f:/doc/afs-and-you.html?ds=inline diff --git a/doc/afs-and-you.html b/doc/afs-and-you.html index f470f83..f2c85c8 100644 --- a/doc/afs-and-you.html +++ b/doc/afs-and-you.html @@ -1,4 +1,4 @@ - +[[!meta title="AFS and You"]]
    @@ -19,7 +19,7 @@
  • Troubleshooting
      -
    1. I'm trying to access my files, fs la says I should have permissions …
      2. +
    2. I'm trying to access my files, fs listacl says I should have permissions …
    3. I'd really prefer that not everyone could list my files, how should I stop …
    4. It was around 6am on a Sunday morning and suddenly I couldn't access my …
    5. It isn't Sunday and I can't get to my files
      6. @@ -28,6 +28,8 @@
      1. Putting Software in a Locker
      2. Acquiring a new locker
        3. +
      3. Find out technical + information about my locker
    6. See Also
    @@ -41,30 +43,30 @@ Credit goes to them, blame goes to him.

    What is AFS?

    -The Andrew File System or AFS is a distributed network file system invented at Carnegie Mellon University as part of Project Andrew (approximately their equivalent of MIT's Project Athena). More importantly, it is the file system used to store most files on Athena today. This includes your personal home directory, the data and websites of many living groups and student groups on campus, and probably some of the software you run (if you ever use Athena clusters). (Though all user directories were migrated from NFS in the summer of 1992, some files probably still remain on NFS and, of course, various file systems are used on personal computers and servers.) +AFS (previously the Andrew File System or ) is a distributed network file system invented at Carnegie Mellon University as part of Project Andrew (approximately their equivalent of MIT's Project Athena). More importantly, it is the file system used to store most files on Athena today. This includes your personal home directory, the data and websites of many living groups and student groups on campus, and probably some of the software you run (if you ever use Athena clusters). (Though most user directories were migrated from NFS in the summer of 1992, some files still remain on NFS and, of course, various file systems are used on personal computers and servers.)

    In Short: AFS is probably where some of the files you care about live

    -For the most part, using AFS, particularly at MIT, is well-hidden and can be used like any other UNIX file system. For some things, you will need to know a bit more. Let's start by defining some terms. +For the most part, using AFS, particularly at MIT, is well-abstracted; For most tasks, it can be used like any other UNIX file system. For a few, you will need to know a bit more. Let's start by defining some terms.

    Some MIT/AFS terminology

    locker
    -For practical purposes, a folder. Probably the what you'll care about most of the time. Technically any directory mountable under /mit, regardless of how its stored. Today, most lockers lockers are stored in AFS. +For practical purposes, a folder. Probably what you'll care about most of the time. Technically any directory with a hesiod FILSYS entry, regardless of how its stored. Most lockers, however, are stored in AFS and are usually accessed as directories in /mit.
    tokens
    -Essentially proof to the AFS servers that you are who you say you are, thus allowing you to access files you are supposed to. Analogous to Kerberos tickets. +Proof to the AFS servers that you are who you say you are, thus allowing you to access files you are supposed to. Technically, a special type of Kerberos ticket.
    cell
    -AFS concept of an "administrative domain of authority." Each cell has its own set of users, groups, and administrators. Analogous to a Kerberos realm. Each top-level directory in /afs corresponds to a cell. The cells you are most likely to care about are athena.mit.edu and sipb.mit.edu. +AFS concept of an "administrative domain of authority." Each cell has its own set of users, groups, and administrators. Analogous to a Kerberos realm. Each top-level directory in /afs generally corresponds to a cell. The cells you are most likely to care about are athena.mit.edu and sipb.mit.edu.

    The Basics

    The Layout of a Typical MIT Locker

    -Every Athena user has a locker (their home directory), which mounts at /mit/<username>. From a technical standpoint, it is stored in the volume user.<username> which is located at /afs/athena.mit.edu/user/<first letter>/<second letter>/<user name>. For example, the user joeuser has a home directory that mounts at /mit/joeuser, is volume user.joeuser, and is accessible at /afs/user/j/o/joeuser. Lockers for projects, software, classes, living groups, and student groups are all mounted at /mit/<lockername> and stored at various places in AFS. +Every Athena user has a locker (their home directory), which mounts at /mit/<username>. From a technical standpoint, it is (almost always) stored in the volume user.<username> which is located at /afs/athena.mit.edu/user/<first letter>/<second letter>/<user name>. For example, the user joeuser has a home directory that mounts at /mit/joeuser, is volume user.joeuser, and is accessible at /afs/athena.mit.edu/user/j/o/joeuser. Lockers for projects, software, classes, living groups, and student groups are all mounted at /mit/<lockername> and stored in various places in AFS.

    @@ -73,33 +75,35 @@ Within each locker, there are (by default) 4 special subdirectories you want to

    Public
    By default, this directory can be read by everyone (and I do mean EVERYONE!), so put files here you want to share with the entire world.
    Private
    -By default, this directory can only be read and can only be listed by you (from AFS, not from web) whereas the files in other directories can (by default) only be read by you, but can be listed by anyone. This means that other people can't see the contents of your files, but they can see what files you have outside of Private +By default, this directory can only be read and can only be listed by you (from AFS, not from web) whereas the files in other directories can (by default) only be read by you, but can be listed by anyone. This means that other people can't see the contents of your files, but they can see the names of the files you have outside of Private
    OldFiles
    -This folder is a link to a read-only copy of a backup of your files (created nightly at 3 a.m.). This copy cannot be edited and does not count towards the locker's quota. (From a technical standpoint, this is a separate volume, user.<username>.backup and is stored only as changes against the current copy.) +This folder is a link to a read-only copy of a backup of your files (created nightly around 3 a.m.). This copy cannot be edited and does not count against the locker's quota. From a technical standpoint, this is a separate volume with .backup appended (e.g. user.<username>.backup ) and is stored only as changes against the current copy.
    www
    -Where you should put a website, if you want one. There is very little special about this directory from an AFS standpoint, but it is world-readable (like Public) and is linked directly to http://www.mit.edu/~<lockername> as well as http://web.mit.edu/<lockername>. +Where you should put a website, if you want one. There is very little special about this directory from an AFS standpoint, but it is world-readable (like Public) and is linked directly to https://www.mit.edu/~<lockername> as well as https://web.mit.edu/<lockername>/www/.

    Accessing Lockers

    From Athena

    -On Athena, you can access a locker either as its full AFS path, if you know it (e.g. /afs/athena.mit.edu/course/6/6.01), or under /mit if it is "attached." Yet a third way is to use tilde expansion and simply cd ~~<locker> (e.g. cd ~~6.01) which will take you to the full path. Often, however, you want to attach lockers because it is easier to refer to them outside of the shell (in a script, for example) and software is set up to run with a path under /mit. There are a few ways to attach a locker: +On Athena, you can access a locker either as its full AFS path, if you know it (e.g. /afs/athena.mit.edu/course/6/6.01), or under /mit if it is "attached." Though you can always use the full path, you often want to attach lockers because it is easier to refer to them and software is set up to run with a path under /mit. There are a few ways to attach a locker:

    -