[OpenAFS] will OpenAFS serve my needs?

[Jason Edgecombe]

Answers inline.

F. Even wrote:
> I'm trying to figure out if OpenAFS can accomplish what I need it to.
>
> Here are my requirements:
>
> All servers are generally AIX unless specified.
>   
I have read of people running openafs on AIX, but I'm not sure how many 
people are running OpenAFS on AIX.

> 01.  3 file servers in distinct geographic parts of the country (while
> of course not the same subnet, all the networks are connected).
> 02.  Each file server will have files that will be unique (I'm
> guessing could be mapped back to unique cells).
>   
You could have all three servers in the same cell. Different paths would 
seamlessly map to difference servers.
> 03.  Each server will need some kind of failover capability (either
> duplicating to a read-only volume or some kind of failover service on
> server side).  Needs to be invisible to the client.
>
>   
Currently, seamless failover is only possible between read-only copies 
of volumes hosted on different servers/partitions. Read-only copies are 
only updated when the  "vos release" command is run as an AFS admin.

That said, there are other options that are not as seamless or have a 
short, but noticeable failover time.
> All of these file servers will be a repository of files for
> applications running on other servers (files will be written from
> other servers and read from others).  Original idea was to use NFS
> where possible and FTP/SAMBA for clients that do not support NFS
> (Windows).
>
> 04.  Each server could have files/images/documents/audio/whatever
> related to a particular topic.  All these files will need to be
> brought together in a shared hierarchy from all of these servers into
> one hierarchy.
>
>   
AFS offers one globally unified filesystem/hierarchy for all files on 
all server. Download the OpenAFS client to see how this works. No need 
to set up a server or get an account.
> Initial design was to have one of the file servers act as a
> centralized connection point, synchronize all files back to it, and
> have all the processing done on it.
>
>   
> I guess I'm curious if I can configure OpenAFS to have space shared
> and sychronized, fully writeable, across all 3 of the servers so it
> could be mounted as one filesystem or one drive letter (windows
> clients).  OR...if this is not possible...how quickly does
> synchronization happen?  If a job were run to pull files together on
> one server....would the replicated copies get updated fairly quickly?
>
>   
The data could be split across the three servers according to the 
directory structure. All files appear in one filesystem as one drive 
letter no matter what server they are located on.

Synchronization of read-write to read-only copies is done manually and 
depends on the amount of data that has changed since the last sync. That 
said, you could script it to happen upon job completion.
> Right now the plan is:
>
> Application servers NFS mount from the file server in each area, right
> out files to it.  Other servers will mount those same spots to take
> files and do things w/ them.  Some Windows servers will need to write
> files to the servers.  Where they need to write, it was going to be
> via FTP.  Windows clients will need to retrieve files after jobs are
> ran (the job that will pull files from all the servers).  As of right
> now, one server will be chosen as the box that all the files are
> copied to for the jobs to run and the server will run SAMBA.  The
> windows clients will connect to a directory to pull those files that
> have resulted from the job run.  ALSO, Active Directory authentication
> needs to be supported (preferably seemlessly).
>
> Would OpenAFS make any of this easier?
>   

With openafs, the different servers would mount the global AFS 
filesystem and just read or write to certain directories. The openafs 
client seamlessly locates the files on the correct server. You can move 
the files (volumes) between servers without needing to reconfigure the 
clients.

OpenAFS has clients for AIX, Windows, Mac, Linux and many others. The 
server portion runs on AIX, Linux, Unix, Mac OS X and others. The 
windows server is NOT recommended for production, but the windows client 
works just fine.

Active Directory has been successfully used as the AFS Kerberos server. 
Check out these slides: 
http://workshop.openafs.org/afsbpw06/talks/shadow.html

I'll be happy to answer any more questions.

Sincerely,
Jason