[rdiff-backup-users] AW: rdiff-backup-users Digest, Vol 65, Issue 12

[Schaffrath, Rene]

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> Gesendet: Dienstag, 15. April 2008 18:01
> An: address@hidden
> Betreff: rdiff-backup-users Digest, Vol 65, Issue 12
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> Today's Topics:
> 
>    1. inodes and Windows (Josh Nisly)
>    2. Re: inodes and Windows (Charles Marcus)
>    3. Re: inodes and Windows (Josh Nisly)
>    4. Re: inodes and Windows (Charles Marcus)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Mon, 14 Apr 2008 18:08:19 -0500
> From: Josh Nisly <address@hidden>
> Subject: [rdiff-backup-users] inodes and Windows
> To: address@hidden
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> rdiff-backup has a check when renaming a file to prevent it from 
> renaming over the same inode (rpath.py, around line 247). I started 
> porting this check directly to windows, but the more I think 
> about it, 
> the less I'm sure that it's a good idea. On Windows, NTFS 
> theoretically 
> supports hardlinks (Microsoft had to implement it to claim posix 
> compliance), but in practicality it doesn't exist, and isn't 
> supported 
> well, even by Microsoft's own programs. I've never seen a Windows 
> program that even attempts to handle hardlinks, so I'm not sure it's 
> worth trying to handle them in rdiff-backup.
> 
> There are implementations available that attempt to generate inode 
> numbers based on various attributes, but the inode numbers 
> may shift in 
> certain circumstances. I believe that if Windows ever starts using 
> hardlinks, Microsoft will be forced to implement a better API 
> for them, 
> and when they do that, we can use it.
> 
> Because Windows has no concept of inode numbers, the stat 
> function fills 
> in 0 for all files. This obviously triggers the check for 
> renaming over 
> hardlinked files. Here is where I'm not sure what to do. Is 0 a valid 
> inode number on unix? If not, we could just check for that. We could 
> also fill in a known value (maybe -1) in cmodule.c. Yet 
> another option 
> would be to explicitly check os.name, but that could be slow if we're 
> renaming a file on a remote connection.
> 
> Thoughts?
> JoshN
> 
> 
> 
> 
> ------------------------------
> 
> Message: 2
> Date: Tue, 15 Apr 2008 07:34:19 -0400
> From: Charles Marcus <address@hidden>
> Subject: Re: [rdiff-backup-users] inodes and Windows
> To: Josh Nisly <address@hidden>
> Cc: address@hidden
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> On 4/14/2008, Josh Nisly (address@hidden) wrote:
> > I've never seen a Windows program that even attempts to handle 
> > hardlinks, so I'm not sure it's worth trying to handle them in 
> > rdiff-backup.
> 
> Maybe you could check out DataSafe Backup?
> 
> http://sofgem.selfip.com/
> 
> Claims to do just that... its free, but not open source :(
> 
> I'll be testing it sometime in the next few weeks, once I get three 
> projects wrapped up
> 
> -- 
> 
> Best regards,
> 
> Charles
> 
> 
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Tue, 15 Apr 2008 08:09:21 -0500
> From: Josh Nisly <address@hidden>
> Subject: Re: [rdiff-backup-users] inodes and Windows
> To: Charles Marcus <address@hidden>
> Cc: address@hidden
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> Charles Marcus wrote:
> > On 4/15/2008 8:14 AM, Josh Nisly wrote:
> >>>> I've never seen a Windows program that even attempts to handle 
> >>>> hardlinks, so I'm not sure it's worth trying to handle them in 
> >>>> rdiff-backup.
> >
> >>> Maybe you could check out DataSafe Backup?
> >>>
> >>> http://sofgem.selfip.com/
> >
> >> This program is actually doing something different. It 
> claims to use 
> >> hardlinks to save storage space with files that are identical.
> >
> > ??? I was responding to the comment that 'I've never seen a Windows 
> > program that attempts to handle hardlinks...'
> >
> > If thats not what was meant, then maybe the OP should choose their 
> > words more carefully?
> >
> Ah, ok. My mistake. What I was meaning originally was that I've never 
> seen a Windows program that tries to detect files that are already 
> hardlinked, and tries to behave differently based on that fact.
> 
> JoshN
> 
> 
> 
> 
> ------------------------------
> 
> Message: 4
> Date: Tue, 15 Apr 2008 09:24:28 -0400
> From: Charles Marcus <address@hidden>
> Subject: Re: [rdiff-backup-users] inodes and Windows
> To: address@hidden
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> On 4/15/2008 9:09 AM, Josh Nisly wrote:
> > Ah, ok. My mistake. What I was meaning originally was that 
> I've never 
> > seen a Windows program that tries to detect files that are already 
> > hardlinked, and tries to behave differently based on that fact.
> 
> Oh, ok... no worries...
> 

Symantec Backup Exec e.g. does handle symbolic links. You can control
whether it follows the link or just backs up the information about
the link. Sure, it´s not an often used feature but I think rdiff-backup
should at least be able to detect symbolic links and warn the user
about it.

Greetings,
René

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