[OpenAFS] Definitive list of AFS Limits?

Chris Huebsch chris.huebsch@informatik.tu-chemnitz.de
Thu, 21 Jul 2005 09:35:33 +0200 (CEST)


I can provide a limited number of answers to your questions.

On Thu, 21 Jul 2005, Christopher Mason wrote:

> I'm trying to compile a list of the hard limits in AFS below, based on 
> searching the mailing list.  I'm not sure:
> 1) if these limits are out of date (some of the messages are quite old);
> 2) if there are other important limits I've missed out;

Number of ACL-Entries (per directory).

> 3) if there are practical limits besides these hard limits;

You will read very often, that groups cannot be nested into other
groups. This is only true for OpenAFS prior 1.3.80.

AFS uses a mofified KRB4-Protocol for authentication. If you setup a new
cell, KRB-V should be taken into consideration. (Heimdal works very

> 4) of namei/nodei differences.

The nodei-fileserver-interface is only available for "old" Unices. Using
Linux you have "only" namei.

> Minimum file size (overhead): FAQ says 1k file occupies 1k, but doesn't 
> address overhead.

As far as I have seen, files are stored identically on disk, they are
not splitted or merged into larger container-files. I think the normal 
file-system properties of the vice-partitions count.

> Maximum file size: 2GB???  (is this still true?)
> <https://lists.openafs.org/pipermail/openafs-info/2002-November/007006.html>

Large-File-Support is part of 1.3.x
I am not sure about windwos-clients.

> Maximum files in a volume:
Never heard of something like this. (Of course when there is not
enough space... then there isn't)

> Maximum number of servers for a read only volume:

afs.h says:

#define MAXHOSTS  13    /* max hosts per single volume */

I think that is the number you are looking for.

> Total size of largest known AFS installation:

Define "size". The complexity of a cell depends on many properties. The
size of the storage (e.g. Terabytes online) is not the most important.

Some criteriai (examples of "my" cell in ()):

* number and size of partitions (4 of each 400 gb)
* number and quota of volumes (1600, ranging from 5M to 20G)
* number of users (1500)
* number of afs-file-server (4)
* number of clients (pcs, workstations, other servers) (~100)
* number of different operating systems (afs-server and clients)
   (FC1, SL4, Win2k)
* structure of the cell (one place for servers or distributed)
   (central servers)

> Can an AFS volume be grown in size?  Shrunk in size?  While online?

Yes, Yes, and Yes

They can even be moved across servers without anyone noticing 
(although the become locked for a short period of time).

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