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From: Joe LaVigne 
Newsgroups: alt.os.linux.ubuntu
Subject: Re: Question about mount command and location of files
Date: 2 Mar 2007 20:22:42 GMT
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On Fri, 02 Mar 2007 13:23:43 +0000, Chris Fasano wrote:

> On Fri, 02 Mar 2007 04:26:13 +0000, Blue wrote:
>> 
>> Mounting does not shift the files (phyisically). It just allows them to be
>> read. 
> 
> 
> Thank you.  This explanation is (somewhat) what's causing my
> misunderstanding.  If files aren't physically moved by mounting, then if I
> create a directory under hda1 (home/newdirectory) the /newdirectory is
> physically located on hda.
> 
> So why would any files now created under /newdirectory be physically
> located on hdb just because I mounted /dev/hdb1 to /home/newdirectory,
> since as you say "mounting does not shift files physically?"

It doesn't "shift" files.  I makes a mount point.  When you mount a drive,
you are granting access to it.  Your filesystem is not drive dependent. 
So, if you haven't mounted the drive, /newdirectory is part of a
filesystem mounted on hda.  When you mount hdb1 to /newdirectory, it is
now the startpoint for the filesystem on hdb1.

You are thinking very much in Windows terms, where drives each have a
letter, and a very strict (and limited) way in which they are usually
used.  Even Windows can be mounted like we are discussing, though.

> 
> I'm not disputing the answer, just trying to understand how it works, 
> and it's driving me nuts.  I won't post again on this issue; thanks
> again.
> 
> Is there a difference between these two tasks:
> 
> 1. mkdir under /home
> 2. add files to /home/newdirectory
> 3. mount /dev/hdb to /home/newdirectory
> 
> and
> 
> 1. mkdir under /home
> 2. mount /dev/hdb to /home/newdirectory
> 3. add files to /home/newdirectory

Yes.  A monstrous difference.  In example 1, when you add the files, the
mount has not been done, so the files are written to the drive currently
mounted there, which is wherever /home is (note:  You don't intimate, in
this example, that it is on hda1, so it cannot be assumed.  /home could be
anywhere).

In example 2, you mounted the partition to the mountpoint first, so the
files are written to the mounted partition.

> 
> There must be a difference between these tasks.  I'll experiment tonight
> after work.
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