[OpenAFS] new infrastructure-afs home and backup questions

Chris Huebsch chris.huebsch@informatik.tu-chemnitz.de
Wed, 11 May 2005 14:49:37 +0200 (CEST)


On Wed, 11 May 2005, Klaas Hagemann wrote:

> I would recommend to leave the user-home on the local file system and to link 
> all the very important directories into it after login. We suffered under 
> performance-problems, because some applications do save temporary files under 
> users home-directory. With this symlink-solution, you can decide for every 
> application where to store its files and keep afs-volumes smaller.

I guess, your users do not move around, but use the same computer every
day. Do they remote-login into other computers?

Do you create their homes dynamically (via pam_creteuserdir or something
like that)?

> Another point is, that many login-managers (like kdm or gdm) require access 
> to the users-home directory, for which no ticket is available at this point.

Really? I think a correct PAM-configuration does handle that.

I know 3 different installation (2 with AFS, 1 with pam_createuserdir),
which work with <any>DM.

> For the location of  the home-directories i implementet rules where this 
> directories are mountet, eg:
> /afs/cell.name/usr/<first letter of login-name>/login-name
> If you have lots of users, you can devide them into more subdirectories. Then 
> you can find this directories script-based and symlink them under /home/

Yes. That is recommended. But perhaps not usr, but home (i have the
impression, that binaries are in usr-directories).

> 1. user backup-volumes and mount them seperately for the user. So every user 
> can access his backup under a subdirectory.
> A  backup-volume is a logical snapshot of a volume, which needs only very 
> little space on the file-system. You can mount this volume with fs mkmount 
> <volumename>.backup anywehre in afs-space.

Only if the content of the volume does not change too much. If the user
changes all files during 2 vos-backups, the backup-clones need the same
space as the rw-original.

The backups need to be recreated on a regular basis!

> A backup-volumes does not cover hardware-failures...

That is true!

> 2. I did the backup with vos dump and saved the dump-files on a third-party 
> backup-system. Here you have many possibilities to restore older 
> configurations. Read-Only Clones are not useful, because the client will 
> access read-only clones by default and so the home-directory will not work.

Of course they are. You have to mount the rw-originals with "fs mkmount
$HOME <volume> -rw" in order to reach them via $HOME. The ro-clones can
be used as an additional backup. (And this even on an other fileserver!)

Chris Huebsch    www.huebsch-gemacht.de | TU Chemmnitz, Informatik, RNVS
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