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
incremental dumps, so it is somewhat useless to compare two NFS
devices numbers over time. The solution implemented currently is to
considers all NFS devices as being equal when it comes to comparing
directories; this is fairly gross, but there does not seem to be a
better way to go."
The indication that tar has recognized a particular file as part of an
NFS mount is a leading 1 in the entry of a Version 2 formatted tar
snaphots file, as described in http://www.gnu.org/software/tar/manual/html_node/tar_170.html
. As I stated in the initial post, tar does not recognize that it is
working on a NFS mounted area of the file system as indicated by the
leading 0 in the snapshots file.
Which brings me back to my original question, why is this happening,
and what can I do to fix it? If I run stat on the files that I am
attempting to create a tar archive out of, it reports that they are
NFS mounted, but tar does not recognize them as such.
Best,
Jordan
On Jan 27, 2008, at 5:57 AM, Vitaly V. Ch wrote:
>"nfs device"
as far as I understand it's sensless expression.
Please detail Your situation
PS. NFS CAN'T SHARE REMOTE DEVICES!!!
On Jan 24, 2008 2:40 PM, Jordan Desroches <[EMAIL PROTECTED]
> wrote:
Hello all,
I'm running into a problem where tar does not seem to recognize that
it is running on a nfs device. The reason I think that is the case are
the leading zeroes in the snapshots file:
[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]/chen..........
[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]/sp.... etc, etc
this is causing some trouble, as when the nfs device number changes,
all of a sudden there is a full backup instead of an incremental. tar
is being called through AMANDA.
I have seen the same results under two environments:
Ubuntu Edgy
GNU tar-1.15.91-2
kernel: 2.6.17-12-generic
Ubuntu Gutsy
GNU tar-1.18-2
kernel 2.6.22-14-generic
any insights that might help me track down why tar does not recognize
nfs?
Thanks for you help!
Jordan Desroches
