Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Kirk Strauser
I use Amanda to make nightly backups of a bunch of servers using GNU tar. 
However, gtar doesn't seem to respect its --one-file-system flag with /proc. 
Amanda runs a variation of this command:

# /usr/local/bin/gtar --create --file - --directory / --one-file-system 
--sparse --ignore-failed-read --totals .  /dev/null
/usr/local/bin/gtar: ./proc: file changed as we read it

Before I file a bug report, can anyone think of a legitimate reason why gtar 
would be touching /proc at all?

Kirk

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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Daniel Staal

On Fri, November 18, 2011 10:34 am, Kirk Strauser wrote:
 I use Amanda to make nightly backups of a bunch of servers using GNU tar.
 However, gtar doesn't seem to respect its --one-file-system flag with
 /proc. Amanda runs a variation of this command:

 # /usr/local/bin/gtar --create --file - --directory /
 --one-file-system --sparse --ignore-failed-read --totals .  /dev/null
 /usr/local/bin/gtar: ./proc: file changed as we read it

 Before I file a bug report, can anyone think of a legitimate reason why
 gtar would be touching /proc at all?

Just a guess, really but:

/proc is a file on /.  /proc/* are files on /proc.  The former is still on
the root filesystem (if only as a directory stub to be used as a
mountpoint), so reading it isn't leaving that filesystem.  Reading
anything *in* it would be.

Just a thought.

Daniel T. Staal

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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Michael Sierchio
On Fri, Nov 18, 2011 at 8:59 AM, Daniel Staal dst...@usa.net wrote:

 /proc is a file on /.  /proc/* are files on /proc.  The former is still on
 the root filesystem (if only as a directory stub to be used as a
 mountpoint), so reading it isn't leaving that filesystem.  Reading
 anything *in* it would be.

 Just a thought.

And a good one.  Yes, that's it.  It isn't crossing the mount point,
but the mount point is part of the root filesystem.

If you really want it to ignore the mount point itself, set the nodump
flag and tell gtar to honor it:

 chflags nodump /proc
 gtar your options --nodump
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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Robert Bonomi
 From owner-freebsd-questi...@freebsd.org  Fri Nov 18 09:36:09 2011
 From: Kirk Strauser k...@strauser.com
 Date: Fri, 18 Nov 2011 09:34:18 -0600
 To: FreeBSD Questions ML freebsd-questions@freebsd.org
 Subject: Shouldn't GNU tar be ignoring /proc with --one-file-system?

 I use Amanda to make nightly backups of a bunch of servers using GNU tar. Howe
 ver, gtar doesn't seem to respect its --one-file-system flag with /proc. Amand
 a runs a variation of this command:

Don't blame the software.

It is just doing *exactly* what you told it to. :)


 # /usr/local/bin/gtar --create --file - --directory / --one-file-system 
 --sparse --ignore-failed-read --totals .  /dev/null
 /usr/local/bin/gtar: ./proc: file changed as we read it

 Before I file a bug report, can anyone think of a legitimate reason why gtar 
 would be touching /proc at all?

Yup.  You (or more properly, Amanda) _told_ it to.

See the output of 'mount(8)' for the names of all the mounted filesystems on
your machine.  

*NOTE*WELL* that '/proc' is *not* a separate filesystem.  It is merely a
_directory_ with a bunch of 'special' files in it.

The 'error message' is accurate -- but it is _just_ a 'warning', and -- in 
*this*
circumstance -- _totally_ innocuous.

If you want to suppress generation of that error, simply add an '--exclude' for
/proc to the Amanda run.


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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Matthew Seaman
On 18/11/2011 17:18, Michael Sierchio wrote:
 On Fri, Nov 18, 2011 at 8:59 AM, Daniel Staal dst...@usa.net wrote:
 
  /proc is a file on /.  /proc/* are files on /proc.  The former is still on
  the root filesystem (if only as a directory stub to be used as a
  mountpoint), so reading it isn't leaving that filesystem.  Reading
  anything *in* it would be.
 
  Just a thought.

 And a good one.  Yes, that's it.  It isn't crossing the mount point,
 but the mount point is part of the root filesystem.

I find it quite astonishing that /proc would deliberately behave
differently to *every other* filesystem available.  The mountpoint
should belong to the filesystem mounted on it.

Cheers,

Matthew

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  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
JID: matt...@infracaninophile.co.uk   Kent, CT11 9PW



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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Kirk Strauser
On Nov 18, 2011, at 11:27 AM, Robert Bonomi wrote:

 See the output of 'mount(8)' for the names of all the mounted filesystems on
 your machine.  

$ mount | grep proc
procfs on /proc (procfs, local)

 
 *NOTE*WELL* that '/proc' is *not* a separate filesystem.  It is merely a
 _directory_ with a bunch of 'special' files in it.

I'm confused here. In what way isn't /proc a separate filesystem? It's even 
called procfs.

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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Michael Sierchio
On Fri, Nov 18, 2011 at 9:27 AM, Matthew Seaman
m.sea...@infracaninophile.co.uk wrote:

 I find it quite astonishing that /proc would deliberately behave
 differently to *every other* filesystem available.  The mountpoint
 should belong to the filesystem mounted on it.

I have an idea what you mean by belong to in this case and - if I'm
right, you're wrong :-)

A mount point has an inode in the parent filesystem, right?  Good,
glad we cleared that up.

Unless you set the 'nodump' flag, and tell tar/gtar/tarsnap/dump to
honor the flag, the archive will have an entry for the mount point.
The 'one-file-system' flags tells gtar not to traverse mount points,
but it will certainly see the mount point and include it in the
archive, along with its modes, flags, atime, mtime, etc. etc.  If
those changed between the time if took a peek at the directory and the
time it attempted to include it in the archive, you'll see those
advisory warnings (which may be ignored in this case).
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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Daniel Feenberg



On Fri, 18 Nov 2011, Kirk Strauser wrote:


On Nov 18, 2011, at 11:27 AM, Robert Bonomi wrote:


See the output of 'mount(8)' for the names of all the mounted filesystems on
your machine.


$ mount | grep proc
procfs on /proc (procfs, local)



*NOTE*WELL* that '/proc' is *not* a separate filesystem.  It is merely a
_directory_ with a bunch of 'special' files in it.


I'm confused here. In what way isn't /proc a separate filesystem? It's 
even called procfs.


I just went to an 8.1 system as root and did:

   umount /proc

and /proc dismounted leaving an empty directory in route. I then went

   mount /proc

and /proc was mounted again, using the parameters in /etc/fstab. Surely
that means that going from / to /proc is crossing a filesystem boundary.
To me that suggests it is a separate filesystem, and typically /proc is
filled with stuff that you wouldn't want to recurse through, so I wouldn't
think it a good candidate for special casing as non-mounted.

Daniel Feenberg
NBER



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Re: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread perryh
Kirk Strauser k...@strauser.com wrote:

 On Nov 18, 2011, at 11:27 AM, Robert Bonomi wrote:

  See the output of 'mount(8)' for the names of all the mounted 
  filesystems on your machine.

 $ mount | grep proc
 procfs on /proc (procfs, local)

  *NOTE*WELL* that '/proc' is *not* a separate filesystem.  It 
  is merely a _directory_ with a bunch of 'special' files in it.

 I'm confused here. In what way isn't /proc a separate filesystem? 
 It's even called procfs.
 
It's Bonomi who is confused.  I suspect he doesn't have procfs 
configured -- so of course its mountpoint is just a directory --
*on his system*.  The OP _does_ have procfs configured, or the
question wouldn't have arisen.
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RE: Shouldn't GNU tar be ignoring /proc with --one-file-system?

2011-11-18 Thread Terrence Koeman
 -Original Message-
 From: owner-freebsd-questi...@freebsd.org [mailto:owner-freebsd-
 questi...@freebsd.org] On Behalf Of Daniel Staal
 Sent: Friday, November 18, 2011 18:00
 To: freebsd-questions@freebsd.org
 Subject: Re: Shouldn't GNU tar be ignoring /proc with --one-file-
 system?


 On Fri, November 18, 2011 10:34 am, Kirk Strauser wrote:
  I use Amanda to make nightly backups of a bunch of servers using GNU
 tar.
  However, gtar doesn't seem to respect its --one-file-system flag with
  /proc. Amanda runs a variation of this command:
 
  # /usr/local/bin/gtar --create --file - --directory /
  --one-file-system --sparse --ignore-failed-read --totals . 
 /dev/null
  /usr/local/bin/gtar: ./proc: file changed as we read it
 
  Before I file a bug report, can anyone think of a legitimate reason
 why
  gtar would be touching /proc at all?

 Just a guess, really but:

 /proc is a file on /.  /proc/* are files on /proc.  The former is still
 on
 the root filesystem (if only as a directory stub to be used as a
 mountpoint), so reading it isn't leaving that filesystem.  Reading
 anything *in* it would be.

 Just a thought.


However, the file /proc on fs / should not be changing since a filesystem /proc 
is mounted over it. The message ./proc: file changed as we read it indicates 
whatever /proc it is trying to read did change...

--
Regards,
T. Koeman, MTh/BSc/BPsy; Technical Monk

MediaMonks B.V. (www.mediamonks.com)
Please quote relevant replies in correspondence.



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