Subject: Re: Which snapshot strategy to use? was: How to capture all file system writes (fwd)
To: gabriel rosenkoetter <gr@eclipsed.net>
From: Jason Thorpe <thorpej@wasabisystems.com>
List: tech-kern
Date: 10/23/2003 14:03:03
On Thursday, October 23, 2003, at 01:02  PM, gabriel rosenkoetter wrote:

> Jason, I see why the normal techniques for making a snapshot file
> system would be pathologically wrong for LFS. But, um, what would be
> *right*?

Remember, all new writes to an LFS are appended to the "end" of the 
file system, and the cleaner garbage-collects old (no longer valid) 
data and re-compacts the segments to provide more space at the "end".

You want a snapshot?  Suspend the cleaner, and then provide a view of 
the older data (there are obviously other details to be worked out 
here, but you get the idea.)

         -- Jason R. Thorpe <thorpej@wasabisystems.com>