[OpenAFS] AFS design question: implementing AFS over a highly-distributed, low-bandwidth network

Chaz Chandler clc31@inbox.com
Thu, 15 Jan 2009 14:27:40 -0800

> You can provide your users with scripts to run to prioritize the client
> for their current location.

Okay, not a problem, but I take it that means there is no public =
repository for scripts like these?

>> The way I understand the volume access is that even if a volume is
>> mounted R/W, its R/O vol is accessed until a write operation, in which
>> case all further access (including reads) are from the R/W vol.  If so,
>> then a user should ideally be able to use the local server for most
>> reads.
> There are two types of mount points:  normal and read-write.   If all of
> the mount points are normal, then a readonly replica is preferred over a
> read-write volume.   If there is no readonly replica, then the readwrite
> is used.

In my experience, a volume that's not explicity mounted R/W is R/O under =
/afs/cell .
So write access is only possible, then, through /afs/.cell and must be =
released before the result shows up under /afs/cell ?

linux1:/afs/cell=23 kinit admin
Password for admin=40CELL:
linux1:/afs/cell=23 aklog
linux1:/afs/cell=23 tokens

Tokens held by the Cache Manager:

User's (AFS ID 1) tokens for afs=40cell =5BExpires Jan 16 17:04=5D
   --End of list--
linux1:/afs/cell=23 fs lsm *
'test' is a mount point for volume '%test'
'ARCHIVE' is a mount point for volume '=23archive'
linux1:/afs/cell=23 fs listacl ARCHIVE
Access list for ARCHIVE is
Normal rights:
  system:administrators rlidwka
linux1:/afs/cell=23 cd ARCHIVE
linux1:/afs/cell/ARCHIVE=23 touch testfile
touch: cannot touch =60testfile': Read-only file system
linux1:/afs/cell=23 cd ../test
linux1:/afs/cell/test=23 fs listacl .
Access list for . is
Normal rights:
  system:administrators rlidwka
  system:authuser rl
linux1:/afs/cell/test=23 touch testfile
linux1:/afs/cell/test=23 ls -l testfile
-rw-r--r-- 1 bin root 0 Jan 15 17:05 testfile

So, maybe it's just a slight difference, but a not explicity-RW-mounted =
volume is effectively RO if the RO volume is available, right?  So I can =
mount a volume =22normally=22 and be accessing the RO vol for reads, but =
not then be able to write to the RW vol without changing the path to =
/afs/.cell .  My concern is with how to best mount volumes, especially =
under the three scenarios listed in the original email (sfw repo, group =
dir, and user dir).

>> The files regular users are concerned with are mostly documents, images,
>> and presentations.  Their heavy sharing is usually confined to a small
>> set of small files (usually less that 1MB each); sets change as projects
>> change (weekly/monthly).  Still, it takes about 1 minute to transfer 1MB
>> across the VPN -- not insignificant.
> What operating system?

The clients run on linux 2.6, openbsd 4.4, windows xp sp3, and (forgot to =
mention before) max os 10.4.  The users do their work from the mac and xp =