[OpenAFS] Questions about OpenAFS "reality"

Horst Birthelmer horst@riback.net
Tue, 13 Dec 2005 10:44:28 +0100

On Dec 13, 2005, at 1:20 PM, Leroy Tennison wrote:

> I am just learning OpenAFS and am very impressed with what I see so  
> far.  As a result I'm now interested in getting a broad overall  
> picture of it and have several questions.
> A recent post stated that they had about 7000 users in a single  
> cell, I'm wondering what a realistic maximum is (assume 'average'  
> end user file activity - nothing extraordinary).  I saw in the  
> archives a refernce to 45k and a statement that UMich had 100,000.   
> Are these (especially the 100,000 for UMich) confirmed numbers?  If  
> anyone out there has a larger cell or knows of someone who does  
> could you provide specifics?  Right now I'm not so concerned with  
> how many file servers I would have to have or other particulars as  
> I am about what a realistic limit is with a proper configuration.

The increasing number of users isn't primarily related to the number  
of the fileservers (these are very easily addable to a cell) but to  
the database servers. If you have a very heavy 'loaded' cell the  
calls to the protection service (ptserver) are worse than teh  
quantity of any other call in the cell. You can design your volume  
location so well, that it scales almost optimal for file access, but  
you still have those calls for permissions from the fileservers  
ending up at a smaller number of protection servers.
(... just some thoughts about what you have to consider in the design  
of such a large cell)

If I'm not terribly mistaken there were cells with more than 130,000  
users around some years ago, but I don't know how 'active' those  
users really were.

> How does AFS compare in administrative burden compared to the  
> common PC NOSes (NetWare and AD)?  Is it more intensive, less or  
> about the same for a given type of user population?  A related  
> question is how "sensitive" is it, do you have to be overly careful  
> in order for things to work correctly?

If you're looking for a fancy graphical administration tool like a  
Windows server will provide.
I don't know of any.

AFS administration is completely scriptable, so after some time in  
administering your cell, you'll end up with some nifty scripts or  
small programs doing almost everything of your daily work.
Maybe some automatic work done at night as well :-)

> How stable and trouble free is the Windows client?  (I saw a  
> statement that the Windows server was considered experimental and  
> not being maintained).

The later statement unfortunately is true, but the client is used by  
many people and is well maintained. ;-)
I never had any major problems with the client, but I'm not using it  
that heavily.

> Is there a Linux GUI for day-to-day administration?
Not that I know of. After some time you don't need it. Believe  
me ... ;-)

> What is the status of server-side byte-range locking?  If this  
> isn't a near-term reality what alternatives do people use (SQL  
> server is obviously a possibility, are there other alternatives for  
> "MS Access" style databases and other byte-range locking needs)?
If you want to use that for databases put into AFS.
Don't ...

And besides, what do you gain from a database where you share the  
files? Maybe for Access it's useful, but if we're talking about big  
databases, you shouldn't do that.

> What are people doing for printing, particularly Windows printing?

They use Samba, if you want to print from windows boxes and your  
servers are UNIX. Or use CUPS, which is also very portable.
But that's a completely different story.

> What about workstation customization (consistent look and feel from  
> workstation to workstation, workstation restrictions, etc.)?  What  
> are the alternatives there?
That depends completely on the workstation, doesn't it?
This is not really related to AFS. AFS just provides a nice way of  
having the same files on all the workstations in the same place (nice  
feature the global namespace, isn't it?)

> I'm not looking for detailed responses just reasonable  
> approximations of "OpenAAFS reality", thank you for any replies.

AFS is very well suited for large hetrogeneous environments with a  
lot of servers lots of users and where scalability is really a 'must