[OpenAFS] fine-grained incrementals?

[Jeffrey Hutzelman]

On Tuesday, February 01, 2005 02:50:04 PM -0500 "John S. Bucy" 
<bucy-openafs-info@gloop.org> wrote:

> looking at src/volser/dumpstuff.c, it appears that dumps are done in
> ascending vnode order.  AFAIK, rename is a first-class operation so it
> should  only dirty the source and dest dirs.

Dumps are currently done in ascending vnode order, directories first, then 
plain files.  But there is nothing which says it must always be that way.

Rename is indeed a first-class operation.


However, I believe Sergio is on the right track here.  You don't want to 
compute deltas on entire dumps, because (1) that means you have to do a 
full dump every time, which consumes more cycles and bandwidth, and (2) it 
won't work with compressed dumps.

You really want per-file deltas.  Ideally, you want the volserver to 
generate them, rather than having to do a normal whole-file incremental and 
compare it to a previous dump -- otherwise, you still haven't saved 
bandwidth, and you've increased the storage requirements on the machine 
doing the backup, possibly by a very large amount.


As far as processing volume dumps is concerned, take a look at my dumpscan 
tools (currently in /afs/cs.cmu.edu/project/systems-jhutz/dumpscan).  They 
provide libraries for parsing and emitting volume dumps, and a few tools as 
well.

-- Jeff