Where to start?

[Eric Anderson]

On 01/23/07 08:35, Oliver Fromme wrote:
> Eric Anderson wrote:
>  > Oliver Fromme wrote:
>  > > Vasil Dimov wrote:
>  > > > This thing still looks to me like roping your chest to your leg (instead
>  > > > of to an unmovable object) in order to avoid falling, but I might be
>  > > > wrong...
>  > > 
>  > > True, it's certainly not a clean nor efficient solution.
>  > > But Mike has a valid point that it would enable people to
>  > > turn on journaling on existing file systems, without the
>  > > need for repartitioning or adding a disk.  It would be a
>  > > nice way to _quickly_ set up journaling, for testing
>  > > purposes, or simply for curiosity.
>  > 
>  > Why not disable swap, use the swap partition as the new journaling 
>  > device, and then enable vn-backed swap for the system?
> 
> Nice idea.  Indeed, that would probably work, if the swap
> is large enough to hold the journal.
> 
> By the way, what happens if you put a swap file on a
> journaled file system?  Will the page-out actions also
> be journaled?

Yep.  gjournal has no way to know (right now) that it is journaling a 
swap file, etc.  It's just a block device journal, so anything that hits 
the disk, goes through the journal.  I'm not sure how this impacts 
performance, if it does at all.


>  > > BTW, I think in Solaris you can also add journaling to an
>  > > existing UFS partition on the fly, without the need for
>  > > newfs or adding space.  (Provided that there is enough
>  > > free space inside the existing file system, of course.)
>  > 
>  > Sure - many journaling fs have that ability.  There's been several 
>  > attempts in the past to add journaling to our UFS2, without completion.
> 
> Yes, I know.  But now there is PJD's gjournal.  :-)
> 
> Best regards
>    Oliver
> 


Eric