Re: WAPBL and snapshots

[Juergen Hannken-Illjes <hannken%eis.cs.tu-bs.de@localhost>]

On Wed, May 26, 2010 at 10:27:31PM -0400, Louis Guillaume wrote:
> Hi,
> 
> I've been wanting to use `log' on my ffs filesystems for a long time, 
> but I keep getting scared away by this "caveat" in the wabpl(4) man page:
> 
>  "File system snapshots (fss(4)) and quotas do not yet work with
>   WAPBL."
> 

Snapshots should work with WAPBL enabled file systems.  I use "dump -x"
on a logging NetBSD-5 machine two times a day.  If I remember right
I had to increase the log size (tunefs).

> I use `dump -x' for backups. So essentially I'm SOL with regards to 
> journalling!
> 
> At least maybe until LVM comes into the stable branches with it's own 
> snapshot facility. But then LVM comes with a stiff warning...
> 
>  "Snapshot feature is not fully implemented in LVM in NetBSD and
>   should not be used in production."
> 
> Aye! And there's no real indication that LVM plays nice with WAPBL 
> either (although I understand that LVM provides a separate layer of 
> abstraction that isn't a file system.)
> 
> I've taken to ignoring the comical "bug" in the fss(4) man page:
> 
>  "This driver is experimental. Be sure you have a backup before
>   you use it."
> 
> It has worked fine for me for years. (Backups happen every night with 
> fss snapshots via `dump -x'.)

So may be it is the time to declare snapshots stable?

> What it all boils down to is: What's the best approach to doing online 
> backups of a NetBSD system while incorporating journalled file systems?
> 
> So far I feel lucky that fss works for me despite its 
> "experimental"-ness; and luck isn't something I like to count on with 
> computers. Any advice would be most helpful. Thanks,
> 
> Louis
> 

-- 
Juergen Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig 
(Germany)