On Thu, Feb 08, 2007 at 05:03:33PM +0100, Stefan 'Kaishakunin' Schumacher wrote:
>Also sprach George Georgalis (george@galis.org)
>> I'd like to begin implementing ffs snapshots. My understanding is
>> that means I can create a file, in an instant, which I can mount
>> for access to the entire filesystem as it existed at that moment
>> in time. Which is possible because by creating the snapshot, I'm
>> instructing the kernel to write diffs to the snapshot file as
>> changes are made to the live filesystem, and mounting a snapshot
>> file presents a mount point which is an application of those diffs
>> in real time. with a limit of something like 8 snapshot files
>> existing at any given time.
>> 
>> Is that how ffs snapshots are implemented in NetBSD? I cannot find
>> _any_ documentation on this, is it written up somewhere?
>> 
>> "apropos snapshot" to the rescue, I do have a couple manpages
>> now. Is there any guide/html doc?
>
>AFAIK there is no more documentation on FFS than what is in the man
>pages. I wrote an article about backup/recovery which covers also ffs,
>but it is in German langugage.

Unfortunately, ...I don't read German.


>However, fss can be used to create a device (/dev/fss[0-4]) which than
>represents the status of the source directory. This device can be
>dumped, mounted or whatever you like. The backup file can be discarded
>with -x, and since I don't know what it is useful for, I do so every
>time I use fss.
>
>I use this for dumping my home slice:
> fssconfig -c -x fss0 /home/ /tmp/
> dump -0 -a -f homedump  /dev/fss0
> fssconfig -u
>
>Instead of dump you could also do a:
> mount /dev/fss0 /mnt/ 
> tar cf home.tar /mnt/
>Or whatever you like. 

Thanks, I really didn't expect such a simple process, and native
to generic.  Exactly what you wrote would be a nice mini section
of the NetBSD Guide (in cc).

I don't think a lot of people know of this really useful feature.

// George



-- 
George Georgalis, systems architect, administrator <IXOYE><