Michael Stowe wrote at about 12:44:51 -0600 on Monday, February 7, 2011:
> > There was a thread a little while back warning about junction point
> > and Windows Vista/7. Also, the Wikki
> > (http://sourceforge.net/apps/mediawiki/backuppc/index.php?title=Common_backup_excludes)
> > talks about the need to exclude Junction points to avoid duplicate
> > backup trees.
> >
> > But it seems to me that at least when using cygwin rsync, that
> > junction points are treated as symlinks so that there doesn't appear
> > to be any duplication in backups.
> >
> > The only issue may be in restoring in that cygwin rsync won't
> > distinguish between true symlinks and junction points which are
> > different animals in the Windows world.
> >
> > Am I missing something?
>
> I don't *think* you are -- junction points have been around since Windows
> 2000 or so, and are best described as a kind of limited symbolic link --
> to be confusingly replaced in Vista with NTFS symbolic links (symlinks)
> which are still called "junction points" for historical reasons.
>
> These are not to be confused with "directory junctions," which was kind of
> the missing piece of a symbolic link -- and NTFS *does* also do hard
> links. On the plus side, in more recent versions of NTFS, although the
> implementation ultimately is reparse point weirdness, behaves pretty much
> like POSIX symbolic and hard links.
>
> I'll whang together a chart:
> POSIX | Windows 7 | Older Windows
> -----------------------------------------------------
> symbolic link | soft link or symlink | junction point/directory junction
> hard link | hard link | hard link
>
> Last I checked, cygwin/rsync/tar treated modern Windows symbolic links
> sanely, and treated hard links like unrelated copies of the same file.
> I'm not sure if this is still the case or what the ramifications are for
> recovery.
>
Thanks for the additional clarification!
Now just to be extra certain, am I correct in my observation that
while Win7 add lots of junction points (which as we both agree are
treated as symbolic links), it does not add any hard links.
So, if so, then there really shouldn't be any backup duplication
problem unless the *user* introduces his/her own new hard links either
via data or new program installs. But I also haven't seen many (if
any) hard links in typical commercial software.
So, I am concluding that from a backup perspective I don't need to
worry about data duplication.
---
On a side note, I *am* looking for a good way to cleanly list all the
junction points so that I can periodically catalog them for potential
future restore.
Note I tried "dir /aL /s" but it doesn't give a very clean listing
plus it seems to itself get hung up on junction loops. So, is there
any good code (either cmd.exe, powershell, or cgywin) to find all
junction points and list them in a simple 2-column like list
consisting of the "source" and the "target" (note standard cygwin
'find' or 'ls' won't help since it doesn't distinguish between
symlinks and junction points)
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