[OpenAFS-devel] Patches for Openafs compression support

[Peter Somogyi]

On Thursday 06 January 2005 19.40, Jeffrey Hutzelman wrote:
> I'm aware of how volume moves work.  It is not the case that a special
> VolForwardZ would be necessary to control whether moves were done using
> compression.  Instead, I would expect the source volserver (the one to
> which you make the VolForward call) to determine the capabilities of each
> target server and behave appropriately, without user intervention.  Again,
> the client should not need to know or care whether compressed dumps are
> being used.
>
> Note that this mechanism is not strictly required -- correct behaviour can
> be obtained simply by not turning on the generation of compressed dumps
> until all servers in the cell are new enough to support them.  However, I
> expect that transition to using the new functionality would be eased by
> allowing AFSVolForward to do automatic capability detection.  This would,
> for example, allow a site to deploy a test server using the new compression
> code, and easily move volumes onto and off of the test server.

I have the following problems/questions with this approach:
- is it good to use the same compression level for storing and transmitting 
data?
- is it good to specify the same compression settings (whether to compress, 
and level) for a whole volserver process? For example: when some of the 
volumes on that server has RO sites with fast connection, and there are some 
others with slow connection to RO sites? (Perhaps it would require a new 
config file or database where a table describes for each volume whether to 
use compression and level)
- I don't understand how do you mean the auto-detection. Could you explain in 
more details how/when/where to deploy the test server?

> The standard approach is to request and receive new procedure numbers
> before submitting a patch, rather than submitting a patch which uses
> made-up or private-use numbers.  This prevents the unfortunate situation in
OK. I will request after the design accepted (if needed). Thanks.

Peter