[zfs-discuss] File level snapshots in ZFS?

[Manoj Joseph]

Richard Elling wrote:
> Atul Vidwansa wrote:
>> Hi Richard,
>>    I am not talking about source(ASCII) files. How about versioning
>> production data? I talked about file level snapshots because
>> snapshotting entire filesystem does not make sense when application is
>> changing just few files at a time.
> 
> CVS supports binary files.  The nice thing about version control systems
> is that you can annotate the versions.  With ZFS snapshots, you don't get
> annotations.

Sure version control systems do file versioning. But, ZFS with its COW 
brings a new way of doing this.

I do not see applications like emacs, star office etc using
SCCS/CVS. But I can easily see then using file snapshots if zfs were to 
offer it (am conveniently ignoring portability).

It was suggested that filesystem snapshots be used to achieve the same 
purpose. It would not work, if you have to roll back one file change but 
not others...

Extended attributes could potentially be used to annotate file 
snapshots... ;)

I can also see possibilities with clustered/distributed applications 
(parallel Postgresql perhaps?) needing to commit/revoke across servers 
using this. Layered distributed filesystems could potentially use this 
for recovery.

But I also remember a long thread on this not too long ago going 
nowhere. ;)

Just my $0.02.

-Manoj