Re: [Bug-tar] tar does not recognize nfs device

[Joerg Schilling]

Jordan Desroches <address@hidden> wrote:

> I'll try to be more specific this time. Our institution has a Netapp  
> NAS that exports files via NFS. We are mounting the exports on a  
> heterogenous group of systems, running different OS's. On some of the  
> systems, we have a need to use the incremental option that tar  
> provides on the NFS mounts (what I previously referred to as an NFS  
> device). Each of the NFS mounts has a device number associated with it  
> that is not necessarily static across reboots. According to the tar  
> documentation 
> (http://www.gnu.org/software/automake/manual/tar/Incremental-Dumps.html 
> ), tar has a way of handling this situation:
>
> "Metadata stored in snapshot files include device numbers, which,  
> obviously is supposed to be a non-volatile value. However, it turns  
> out that NFS devices have undependable values when an automounter gets  
> in the picture. This can lead to a great deal of spurious redumping in  

As GNU tar "believes" that it makes sense to create backups that cross
filesystem (mount) boundaries, GNU tar cannot ignore st_dev in backups.
You will probably always get into trouble.

Did you try star? 

ftp://ftp.berlios.de/pub/star/alpha/

star supports "true incremental dumps" from single filesystems and thus is able
ignore the varying st_dev values.

Jörg

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