[olug] Filesystems

Chad Homan choman at gmail.com
Fri Jul 31 18:24:28 UTC 2009 

All,

Mystery Solved?  How to "interrogate" an ext4 file system for ext3 and ext4
files.

Here is what I have found on this topic and am looking for confirmation or
agreement
from my peers and colleagues that what I tracked down is indeed true and my
quest
for global dominance may proceed or I that I have greatly underestimated my
powers
of investigation ;).

According to my research on this matter.  Apparently the big shift for ext4
is that files
are stored in extents format.  During a conversion, "extents" is one of the
flags one
uses to "tune" the filesystem for ext4.

So looking into extents and slightly changing path on what to look for on my
filesystem.
I found reference to a chattr command.  On my ubuntu system, the man page
makes
reference to a "e" flag that cannot be changed by chattr because it is
"permanent" (for
lack of a better word) flag once set.

This led me to the lsattr command which displays the file attributes,
including the "e" flag.

So began my tests.
  - On an ext3 system, an lsattr showed pretty much no file with the "e"
flag.
  - On a freshly installed ext4 system, pretty much every file had the "e"
flag.
  - So on a freshly converted system, no file appeared to have the "e" flag.

          * I touched a file, and it showed the "e" flag.
          * I copied a file, it to had the "e" flag.
          * And for the real test, I moved a file and it maintained NO "e"
flag, thus
            still in ext3 format.

So I think this is solved.  Please help confirm this.
In the end happy converting.


Chad, CISSP
Sent from Lawndale, CA, United States
Jonathan Swift<http://www.brainyquote.com/quotes/authors/j/jonathan_swift.html>
- "May you live every day of your life."

On Tue, Jul 21, 2009 at 11:48 AM, Kevin <sharpestmarble at gmail.com> wrote:

> [root at kevin-sandbox ~]# cat ~/bin/update-filesystem.sh
> #!/bin/bash
> mv $1 /filename_of_your_choice
> cp -a /filename_of_your_choice $1
> [root at kevin-sandbox ~]# find / -exec ~/bin/update-filesystem.sh
>
>
>
> On Tue, Jul 21, 2009 at 10:06, T. J. Brumfield<enderandrew at gmail.com>
> wrote:
> > I know tarring the entire filesystem to a new location, and then
> > extracting it back does work. Perhaps you can do this folder by folder
> > from within the file system?
> >
> > -- T. J.
> >
> > On Tue, Jul 21, 2009 at 9:44 AM, Chad Homan<choman at gmail.com> wrote:
> >> I believe a "mv" (which would maintain the original inode), then "cp"
> the
> >> file back
> >> to it's original name (new inode) should do the job.  My issue I would
> like
> >> to avoid
> >> renaming the entire filesystem.  Not to mention that I cannot remove the
> >> original
> >> file until after a reboot, in case the file is being used.  However, if
> I
> >> could obtain
> >> a "status" of the FS, My plans for world dominance would nearly be
> complete.
> >>
> >>
> >>
> >> Chad, CISSP
> >> Sent from Los Angeles, CA, United States
> >> Ogden Nash <http://www.brainyquote.com/quotes/authors/o/ogden_nash.html>
>  -
> >> "The trouble with a kitten is that when it grows up, it's always a cat."
> >>
> >> On Tue, Jul 21, 2009 at 8:44 AM, DYNATRON tech <dynatron at gmail.com>
> wrote:
> >>
> >>> just archive the drive and use the archive afterward, rather than the
> >>> original. that should do it. bonus: you have a backup point of the
> entire
> >>> drive....that is...if you have an extra drive to mount up.
> >>>
> >>> i'm a reiser guy, myself.
> >>>
> >>> i've had many smooth rides with ext, though.....except a couple of
> times
> >>> when i was resizing partitions. turned out weird.
> >>>
> >>> On Tue, Jul 21, 2009 at 8:30 AM, T. J. Brumfield <
> enderandrew at gmail.com
> >>> >wrote:
> >>>
> >>> > The files aren't rewritten with extents and such I don't believe with
> >>> > a simple touch.
> >>> >
> >>> > -- T. J.
> >>> >
> >>> > On Tue, Jul 21, 2009 at 8:21 AM, DYNATRON tech<dynatron at gmail.com>
> >>> wrote:
> >>> > > what if you just touch all the files?
> >>> > >
> >>> > > updates the header....might work.
> >>> > >
> >>> > > On Tue, Jul 21, 2009 at 12:47 AM, T. J. Brumfield <
> >>> enderandrew at gmail.com
> >>> > >wrote:
> >>> > >
> >>> > >> I don't know of any way, but if you want to migrate fully, you can
> >>> > >> shrink an ext3 partition down, make a new ext4 partition, copy the
> >>> > >> files so they are written properly on the ext4 partition, mount
> the
> >>> > >> ext4 partition, wipe the ext3 partition, and then resize the ext4
> >>> > >> partition.
> >>> > >>
> >>> > >> -- T. J. Brumfield
> >>> > >>
> >>> > >> On Tue, Jul 21, 2009 at 12:28 AM, Chad Homan<choman at gmail.com>
> wrote:
> >>> > >> > I recently converted one of my systems from ext3 to ext4.
>  According
> >>> > to
> >>> > >> the
> >>> > >> > "guide", over time,
> >>> > >> > the files left at ext3 will migrate to ext4 via updates.  I
> would
> >>> like
> >>> > to
> >>> > >> > know is this.  Is there a
> >>> > >> > way to "interrogate" my file system and figure out the ext3 vs
> ext4
> >>> > >> status
> >>> > >> > of the HDD.
> >>> > >> >
> >>> > >> >
> >>> > >> > Chad, CISSP
> >>> > >> >
> >>> > >> > Joan Crawford<
> >>> > >> http://www.brainyquote.com/quotes/authors/j/joan_crawford.html>
> >>> > >> > - "I, Joan Crawford, I believe in the dollar. Everything I earn,
> I
> >>> > >> > spend."
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> >>> > >
> >>> > >
> >>> > > --
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> >>> > > www.dynatron.org
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