Re: which files took the space
On Fri, 04 Mar 2016 08:11:43 +0100 Frédéric Marchal
<frederic.marchal@wowtechnology.com> wrote:
> On Friday 04 March 2016 07:18:59 Adam Wilson wrote:
> > On Fri, 4 Mar 2016 04:03:01 +1100 Andrew McGlashan
> >
> > <andrew.mcglashan@affinityvision.com.au> wrote:
> > > On 4/03/2016 3:07 AM, Adam Wilson wrote:
> > > > On Fri, 4 Mar 2016 03:03:53 +1100 Andrew McGlashan
> > > >
> > > > <andrew.mcglashan@affinityvision.com.au> wrote:
> > > >> It also may have been files in the file system, but where
> > > >> another file system mount hides them....
> > > >
> > > > What does this mean? Mounts overlapping and hiding other mounts?
> > > >
> > > > Explain, please.
> > >
> > > Yes, this is more likely to happen to the root file system.
> > >
> > > Say you have a bunch of files in /boot, but for some reason you
> > > have a /boot partition that wasn't mounted when those files were
> > > created .... then you mount the /normal/ boot partition over it
> > > and now the other files are now hidden from view, but still
> > > taking up space.
> >
> > So you're talking about creating files in an unmounted partition,
> > and then mounting it, but since file addition happened when the FS
> > was still in an unmounted state, the new files weren't written to
> > the journal?
> >
> > Surely in that case the new files would simply not be registered and
> > act as free space (as if they had been deleted)?
>
> This is not about a caching service. It is about the way the content
> of a mounted disk is made visible to you.
>
> Have you ever wondered how a path name, on your main hard disk, such
> as /mnt/usb becomes a link to a USB disk known to the system
> as /dev/sdd1?
>
> When you type
>
> mount /dev/sdd1 /mnt/usb
>
> It tells the system that, from now on, the directory named "/mnt/usb"
> becomes the entry point to the file system that sit at "/dev/sdd1".
>
> Any call such as "ls /mnt/usb" will list the content of the USB disk
> instead of the usual content of /mnt/usb.
>
> When the device is unmounted, the directory that serves as its mount
> point is restored as a regular directory.
>
> Now, imagine /mnt/usb is not mounted. It is a directory just like any
> other. If you copy files to /mnt/usb, they will be copied to that
> directory and you have access to them as long as no device is mounted
> under /mnt/usb.
Ah. I see. Thank you for that- I was a little bit unsure as to what was
being referred to, until you came and gave an example.
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