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On Fri, 27 Nov 2020 at 17:37, Arne Wiebalck <arne.wiebalck at cern.ch> wrote:
>
> Hi,
>
> I did a quick test (one data point):
>
> - the image build time increased by 10 mins
>    (on a VM, this is more than double compared to gzip)
> - but: the resulting image size is ~30% smaller (421 vs 297 MB)
> - the cleaning time (unpacking on bare metal!) increased by ~30 seconds

30 seconds is a long time, even for bare metal. 134 MB is roughly to a
gigabit of network traffic. So really this comes down to how much
spare capacity you have in your network to handle bursts of these
downloads.

>
> So, lzma looks like a good option to reduce the image size which
> we had to do in our deployment already to address boot issues
> (we removed some packages).
>
> Keeping gzip as the default and offering lzma as an option to
> start with as suggested by Sergii seems like a good way forward.
>
> I also think it would be good to have someone else test as well
> to have another data point :-)
>
> Cheers,
>   Arne
>
>
> On 27.11.20 14:00, Sergii Golovatiuk wrote:
> > Hi,
> >
> > LZMA causes very high CPU and memory usage for creating images, leaving
> > less resources for other processes. If Ironic is running alongside with
> > other services that may cause significant impact for them. I would leave
> > gzip option as default, would introduce --lzma as well as --gzip and use
> > lzma on 5-10% of our CI resources to test how it goes. Then after a
> > significant amount of testing we could turn it on as default. Proper
> > deprecation should be applied here as well IMHO.
> >
> > чт, 26 нояб. 2020 г. в 17:57, Dmitry Tantsur <dtantsur at redhat.com
> > <mailto:dtantsur at redhat.com>>:
> >
> >     Hi folks,
> >
> >     I've been playing with ways to reduce the size of our IPA images.
> >     While package removals can only save us tens of megabytes, switching
> >     from gzip to lzma reduces the size by around a third (from 373M to
> >     217M in my testing).
> >
> >     What's the caveat? The unpacking time increases VERY substantially.
> >     On my nested virt lab the 217M image took around 5 minutes to
> >     unpack. I'm not sure how much it will impact real bare metal, please
> >     feel free to test
> >     https://review.opendev.org/c/openstack/ironic-python-agent-builder/+/764371
> >     and tell me.
> >
> >     So, what do you think? Switching to lzma by default will likely
> >     affect CI run time (assuming we still have DIB jobs somewhere...)
> >     and development environments, but it will also provide a visible
> >     reduction in the image size (which benefit all environments). Large
> >     TripleO images may particularly benefit from this (but also
> >     particularly affected by the unpacking time).
> >
> >     Feedback is very welcome.
> >
> >     Dmitry
> >
> >     --
> >     Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn,
> >     Commercial register: Amtsgericht Muenchen, HRB 153243,
> >     Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs,
> >     Michael O'Neill
> >
> >
> >
> > --
> > SergiiGolovatiuk
> >
> > Senior Software Developer
> >
> > Red Hat <https://www.redhat.com/>
> >
> > <https://www.redhat.com/>
> >
>