JUFS update, and questions.

[Max Khon]

Hello!

On Wed, Mar 10, 2004 at 07:16:09PM -0500, David E. Cross wrote:

> > > Journaled UFS Technology Description
> > > 
> > [... much good stuff deleted]
> > 
> > Not requests for features, just requests as to whether you have
> > considerred these..
> > 
> > Does it have the ability to keep the journal on a separate media?
> > 
> > I have sometimes seen the ability to have a separate journal disk used
> > to good effect. (not a system filesystem, but a journalled database).
> > 
> > Having a separate journal file/disk elsewhere can speed things up by
> > reducing seeks (and other resiliance advantages).
> > I have also seen double logging and remote logging... each of which of
> > course has advantages and disadvantages..
> > 
> > Remote logging allows the log to be "replayed" at real time in teh
> > remote site, leading to an instantaneously correct remote
> > backup/mirror of the local disk. (of course it can not be safely
> > accessed except with special safety requirements.. (e.g ability
> > to shoot an open vnode if teh inode under it is rewritten)
> > 
> > 
> > I notice also that you store pre/post stuff and wonder if this can be
> > used in conjunction with soft-update's need to sometimes roll-back
> > things on the disk?
> 
> It has been thought about, and certainly the design would make it
> trivial at a later point to add.  The system does all of the work
> through vnodes and struct bufs, so they could be backed by "anything" in
> the future (well, within reason).  But for right now its beyond the
> scope of the project.

Do you plan to implement data journalling?

Regards,

/fjoe