rsync - Mar 2004 - Win32 and Backing up open files

I now fully and completely remember why I hate Windows.

I have struggled with the backup semantics options in order to get rsync
able to back up open files, and I got something that appeared like it
should work, but it didn't work.  So I finally broke down and wrote a
holdopen.exe and a tryopen.exe to test my theory, and no matter what
privleges were enabled (backup and restore were enabled), a program
under Windows can _NOT_ open a file which has been opened if the
original opener has not specified read sharing.  No matter what.

A much more careful reading of the docs indicates that backup semantics
only allow you to bypass _security_ restrictions, not sharing
restrictions (as well as allowing access to security information about
the file).

I can't believe it.  This means that most backups under Windows are
completely useless unless programs avoid opening a file without
SHARE_READ.

One backup program claims to be able to back up unshared, open files.  They
say that they do it with a custom kernel driver which allows them direct
access to the file.  This, of course, is beyond the scope of my charter
for modifying rsync.

-- 
 Jason M. Felice
 Cronosys, LLC <http://www.cronosys.com/>
 216.221.4600 x302

On Wed, 2004-03-03 at 07:07, Jason M. Felice wrote:
> I now fully and completely remember why I hate Windows.
> 
Good. Everyone needs reminding now and then :-)
> ... a program
> under Windows can _NOT_ open a file which has been opened if the
> original opener has not specified read sharing.  No matter what.
Yup. That's part of the reason why you have to use "special"
versions of
NTBackup/etc to backup Exchange and SQL servers. As these files are
always in use, there is no way you can read 'em. 

On a Unix system, you can still access/backup your SQL databases as
files - even when they are in use. Whether that's a good idea I leave
for others to discover the hard way... ;-)

Cheers

Jason Haar
Information Security Manager, Trimble Navigation Ltd.
Phone: +64 3 9635 377 Fax: +64 3 9635 417
PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 66D1