On Wednesday, December 06, 2006 09:48:59 AM -0500 Jim Rees <[EMAIL PROTECTED]>
wrote:
We've already got the flag and a mechanism for setting it. It's the
PDiscon pioctl. The flag is not global now but could be.
I suppose I should write something up. I think at this point it might be
better to start from scratch with the old discon code and papers as a
guide rather than to try to port the old code.
The steps are, roughly:
1. Make afs_Analyze fail if disconnected
2. Fix read vnode ops to use cached data if available, else fail
3. Fix write vnode ops to modify the cache, and log the operation
4. Add code to replay the log after reconnection
5. Add code to pickle the vcache and dcache across restarts
6. Write the optimizer
That's full disconnected mode, which is a great idea, but also a fair bit
of work, especially since you left out the key step that makes it all
usable:
7. Design and implement conflict resolution.
I was talking about the "good enough" version you mentioned earlier, which
has also been discussed in the past. That's much simpler because it
replaces all those steps with two:
- Behave as if all fileservers are down
- Allow use of cached data even for vnodes that are not CStatd
-- Jeff
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