UFS2 Snapshot limitiations

[Pietro Cerutti]

On 3/13/07, Bill Moran <wmoran at potentialtech.com> wrote:
> In response to "Pietro Cerutti" <pietro.cerutti at gmail.com>:
>
> > On 3/13/07, Doug Poland <doug at polands.org> wrote:
> > >
> > > On Tue, March 13, 2007 10:10, Bill Moran wrote:
> > > > In response to "Doug Poland" <doug at polands.org>:
> > > >
> > > >> Hello,
> > > >>
> > > >> I seem to recall, but cannot find, the limitation on the number of
> > > >> snapshots allowed on UFS2.  Could someone point me in the right
> > > >> direction please?
> > > >
> > > > The handbook has it:
> > > > http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/snapshots.html
> > > >
> > > Thank you very much.
> > >
> >
> > Sorry for joining the thread, but it's raised my curiosity: what's the
> > reason for this limit?
>
> I'm not 100% sure, but I believe it's because snapshot information is stored
> in the filesystem superblock, and that's all that can fit in the space
> available in the superblock.

This is the same thing that came to my mind, but in the handbook page I found:
"Active snapshots are recorded in the superblock so they are
persistent across unmount and remount operations along with system
reboots."

1) what an "active" snapshot is?
2) is that limit limited (...) to active snapshots?

Tnx

> --
> Bill Moran
> http://www.potentialtech.com
>


-- 
Pietro Cerutti

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