Re: df and du disagree, or "How to get 1.1GB of data onto a 650MB CD"
-------- Original Message --------
From: T <mlist4suntong@yahoo.com>
Apparently from: bounce-debian-user=re2823=safe-mail.net@lists.debian.org
To: debian-user@lists.debian.org
Subject: Re: df and du disagree, or "How to get 1.1GB of data onto a 650MB CD"
Date: Fri, 22 Sep 2006 09:10:19 +0200
> On Fri, 22 Sep 2006 09:14:37 +0100, re2823 wrote:
>
> > I have a strange problem: I have an iso image file which (according to ls)
> > is 569M in size:
> >
> > ...
> >
> > Now for the problem...
> > The relevant line from "df -h":
> > poota:~# df -h
> > Filesystem Size Used Avail Use% Mounted on /root/image.iso
> > 569M 569M 0 100% /root/temp
> >
> > And the result from running "du -sh": poota:~# du -sh temp/
> > 1.1G temp/
> >
> > Just to really baffle me, I've burnt this iso image onto a 650MB CD-ROM,
> > mounted it, and it too has 1.1GB of data on it:
> >
> > poota:~# du -sh /media/cdrom0
> > 1.1G /media/cdrom0
> >
> > But the "df -h" output seems more reasonable: server:~# df -h
> > Filesystem Size Used Avail Use% Mounted on /dev/hdd
> > 569M 569M 0 100% /media/cdrom0
> >
> > Could anyone please tell me how there can be such a huge difference
> > between the output from df and du?
>
> Are you using some kind Live CD? This is actually quite normal for Live
> CDs.
>
No, sorry, no live CD. I'm running a plain-and-simple Debian
install (onto a hard-disk). The iso file "appears" to be a
standard ISO9660 data file ("file image.iso" says "ISO 9660
CD-ROM filesystem data" so I don't think it's anything special.
> > My real problem comes when I want to remove one small file from the file
> > system, and turn it back into an iso - the resulting iso image is 1.1GB
> > (and I can no longer write it to a CD!)
>
> It maybe helpful if you had indicated what CD you are using.
The CD that I'm using for this part is just a standard 70 min,
650MB blank cd-r.
They must
> be using some kind of compression. So,
Do you mean compression as in "zip, gzip, etc"? If so, I don't
see how that would make any difference to the size occupied by
the iso file and size of its contents. Surely 500MB of text files
takes up the same space as 500MB of gzip files - 500MB to be
precise!
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