* Re: [gentoo-dev] RFC: Hosting daily gx86 squashfs images and deltas
@ 2014-01-17 18:53 99% ` Michał Górny
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From: Michał Górny @ 2014-01-17 18:53 UTC (permalink / raw
To: gentoo-dev; +Cc: antarus
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Dnia 2014-01-17, o godz. 10:18:58
Alec Warner <antarus@gentoo.org> napisał(a):
> On Fri, Jan 17, 2014 at 8:27 AM, Michał Górny <mgorny@gentoo.org> wrote:
>
> > Hello, all.
> >
> > I'm using squashfs to hold my Gentoo repositories on all of my systems
> > for some time. As you probably know, this allows me to save space while
> > keeping portage fast. However, it makes updating the tree quite
> > burdensome and time-consuming.
> >
> > We're already hosting daily gx86 tarballs on our mirrors, and deltas
> > made using diffball. Those can be used with Zac's emerge-delta-webrsync
> > to get daily updates done with minimal network overhead. Sadly, it
> > takes the whole process even more time consuming :).
> >
> > Therefore, I'd like to suggest an alternative solution that could help
> > out Gentoo users that use squashfs for gx86 and would like to be able
> > to get daily updates fast and easy.
> >
> > The idea is to host -- along with the tarballs -- daily squashfs images
> > of gx86 in a chosen format. Additionally, the images would come with
> > deltas made using xdelta3 or a similar tool. Those deltas -- with
> > a slight download overhead -- would allow very fast updates
> > of the squashfs.
> >
> > Now some numbers. I did some tests 'converting' late gx86 daily
> > tarballs to squashfs. I've used squashfs 4.2 with LZO compression
> > since it's quite good and very fast.
> >
> > 96M portage-20140108.sqfs
> > 96M portage-20140109.sqfs
> > 96M portage-20140110.sqfs
> > 96M portage-20140111.sqfs
> > 96M portage-20140112.sqfs
> > 96M portage-20140113.sqfs
> > 97M portage-20140114.sqfs
> > 97M portage-20140115.sqfs
> >
> > For deltas, I've used xdelta3 with max compression (-9) and djw
> > secondary compression (it gave ~0.1M smaller files than fgk
> > and ~0.5M gain than with no secondary compression).
> >
> > 4,9M portage-20140108.sqfs-portage-20140109.sqfs.vcdiff.djw
> > 6,3M portage-20140109.sqfs-portage-20140110.sqfs.vcdiff.djw
> > 5,6M portage-20140110.sqfs-portage-20140111.sqfs.vcdiff.djw
> > 8,9M portage-20140111.sqfs-portage-20140112.sqfs.vcdiff.djw
> > 6,3M portage-20140112.sqfs-portage-20140113.sqfs.vcdiff.djw
> > 7,8M portage-20140113.sqfs-portage-20140114.sqfs.vcdiff.djw
> > 8,5M portage-20140114.sqfs-portage-20140115.sqfs.vcdiff.djw
> >
> > As you can see, the deltas are quite large compared to the actual
> > changes. However, we could have expected that since we're diffing
> > a compressed filesystem. What's important, however, is that applying
> > it takes ~2.5 second on my 2 GHz Athlon64.
> >
>
> It wasn't clear to me, are these trees with metadata included?
Yes, full metadata with md5-cache. That's the same thing you get via
'emerge --sync'. And that's why the deltas are so big -- I recall three
big cache updates this week.
--
Best regards,
Michał Górny
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2014-01-17 16:27 [gentoo-dev] RFC: Hosting daily gx86 squashfs images and deltas Michał Górny
2014-01-17 18:18 ` Alec Warner
2014-01-17 18:53 99% ` Michał Górny
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