zeroing out the cloud image filesystem

[Dennis Gilmore]

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El Tue, 21 May 2013 20:54:25 -0400
Andy Grimm <agrimm at gmail.com> escribió:
> On Tue, May 21, 2013 at 5:34 PM, Matthew Miller
> <mattdm at fedoraproject.org>wrote:
> 
> > On Wed, May 15, 2013 at 11:18:04AM -0400, Matthew Miller wrote:
> > > > 2) I also commented out the "Zeroing out empty space"
> > > > postinstall
> > stuff,
> > > > because it drastically increases the image build time for not
> > > > much
> > benefit,
> > > > IMHO.
> > > One time image build cost vs. whatever benefit multipled by every
> > > time
> > the
> > > image is used. :)
> >
> > To put some numbers behind it, the compressed qcow2 image with the
> > dd to zero empty space is 215M out of appliance-creator. Without
> > it, it's 242M.
> >
> 
> Two things here:  First, I did not mean to imply that I thought
> zeroing out the disk was a completely useless operation.  I merely
> was not willing to pay the penalty for building my test image, and I
> was trying to be completely honest about exactly how I built my
> image.    Second, I think one of the reasons this operation annoys me
> is that I'm used to using ami-creator to create filesystem images
> (rather than full-disk images), and in that scenario I start with a
> very small filesystem (1 GB or less) and grow it after it's created.
> The idea of having a 10 GB disk, filling less than 3% of its
> capacity, and then having to write zeros to the other 97%, most of
> which was not actually needed for the install, seems pretty
> suboptimal.  If there are tools to optimize it (fstrim or whatever),
> that's great.  Otherwise, I'd be considering some hack like: make a
> small partition on the disk, do the install, zero out bytes on the
> partition, and then repartition.

its actually completely wasted in the current processes. koji
desparsifies the images when uploading to the hub. so we end up with
10gb files anyway

Dennis
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