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Old 06-19-2008, 05:51 PM
"Michael Wiktowy"
 
Default RPM compression format

Hi,

I just read http://www.linuxformat.co.uk/static/suse11.html where is
mentions that OpenSuSe 11 went with a different compression algorithm
for their rpms (LZMA instead of bz2) and have a few questions:

1) While every distro seems to be coming together on a package
management GUI (PackageKit), does this represent a splintering of
package formats? or is rpm compression algorithm agnostic? Is there
any hope that the various rpm development will start pulling in the
same direction?

2) LZMA appears to have some good characteristics for installation
rpms (tighter compression, 50% decompression time ... at least as
implemented by 7zip ref:
http://www.maximumcompression.com/data/summary_mf4.php ). Is Fedora
planing to follow this switch (or has it already and not advertised it
as a prominent feature) or are there other considerations preventing
that (patent issues?, not suitable for delta rpms?, 200% compression
time)?

/Mike

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Old 06-19-2008, 07:50 PM
Rahul Sundaram
 
Default RPM compression format

Michael Wiktowy wrote:

Hi,

I just read http://www.linuxformat.co.uk/static/suse11.html where is
mentions that OpenSuSe 11 went with a different compression algorithm
for their rpms (LZMA instead of bz2) and have a few questions:

1) While every distro seems to be coming together on a package
management GUI (PackageKit), does this represent a splintering of
package formats? or is rpm compression algorithm agnostic? Is there
any hope that the various rpm development will start pulling in the
same direction?


Distribution have been shipping patches for a long while and that
quantity against rpm seems to be dropping off now looking at SUSE,
Mandriva etc. Compression algorithm doesn't affect the spec file format.



2) LZMA appears to have some good characteristics for installation
rpms (tighter compression, 50% decompression time ... at least as
implemented by 7zip ref:
http://www.maximumcompression.com/data/summary_mf4.php ). Is Fedora
planing to follow this switch (or has it already and not advertised it
as a prominent feature) or are there other considerations preventing
that (patent issues?, not suitable for delta rpms?, 200% compression
time)?


Refer to this RFE I filed a while back at

https://bugzilla.redhat.com/show_bug.cgi?id=441110

Rahul

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Old 06-20-2008, 06:47 AM
Jindrich Novy
 
Default RPM compression format

On Thu, Jun 19, 2008 at 01:51:50PM -0400, Michael Wiktowy wrote:
> Hi,
>
> I just read http://www.linuxformat.co.uk/static/suse11.html where is
> mentions that OpenSuSe 11 went with a different compression algorithm
> for their rpms (LZMA instead of bz2) and have a few questions:
>
> 1) While every distro seems to be coming together on a package
> management GUI (PackageKit), does this represent a splintering of
> package formats? or is rpm compression algorithm agnostic? Is there
> any hope that the various rpm development will start pulling in the
> same direction?

Yes. We already have the LZMA bits in the upstream RPM for a while. So
the support for the LZMA payload compression will occur as soon as the
head RPM lands in rawhide. Support for old gz/bz2 payload remains, so
no regressions will be introduced.
>
> 2) LZMA appears to have some good characteristics for installation
> rpms (tighter compression, 50% decompression time ... at least as
> implemented by 7zip ref:
> http://www.maximumcompression.com/data/summary_mf4.php ). Is Fedora
> planing to follow this switch (or has it already and not advertised it
> as a prominent feature) or are there other considerations preventing
> that (patent issues?, not suitable for delta rpms?, 200% compression
> time)?

Agreed, LZMA shows amazing compression results better that bzip2 with
faster decompression than bz2 in most cases. OTOH it consumes more
memory and compression takes longer, but seems to be feasible with the
-7 compression level (default).

The exact timing for the new rpm release is not clear yet, but there
would be a need of mass rebuild to fully take advantage of the new
compression.

> /Mike
>
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> https://www.redhat.com/mailman/listinfo/fedora-devel-list

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Old 06-20-2008, 07:47 AM
Nigel Metheringham
 
Default RPM compression format

On 20 Jun 2008, at 07:47, Jindrich Novy wrote:


The exact timing for the new rpm release is not clear yet, but there
would be a need of mass rebuild to fully take advantage of the new
compression.



I guess we also need to stage things appropriately so that those
updating to Fedora x (where x is the LZMA supported distro) by using
on-line update (yeah I know its not supported as such but its always
worked well in the past), are able to get the initial upgrade
requirements onto their box (which I guess would be rpm, yum & fedora-
release) without being stymied by an rpm for those packages being
compressed with LZMA when their own rpm cannot cope with it...


Nigel.
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[ - Comments in this message are my own and not ITO opinion/policy - ]

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Old 06-20-2008, 11:03 AM
"KH KH"
 
Default RPM compression format

> I guess we also need to stage things appropriately so that those updating to
> Fedora x (where x is the LZMA supported distro) by using on-line update
> (yeah I know its not supported as such but its always worked well in the
> past), are able to get the initial upgrade requirements onto their box
> (which I guess would be rpm, yum & fedora-release) without being stymied by
> an rpm for those packages being compressed with LZMA when their own rpm
> cannot cope with it...
>
> Nigel.

I think that's already done, on transaction, rpm (yum and co.) always
search for updated version of themselves first.
Well, indeed, rpm compressed with lzma aren't compatible with Fedora yet.
Maybe that's the point we need to fix. Because we cannot install rpm
from SuSE on Fedora (even if that doesn't really make sense unless for
pure contents and we can always package it for Fedora ).
If download size matter, I think it would be better to answear with
deltarpms instead.
Now maybe we can split the question of the lzma "support" in rpm
itself with the question to "use" lzma in rpm, distro wide.

Anyone ever submitted a RFC bug about this ?

Nicolas (kwizart)

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Old 06-20-2008, 11:07 AM
"Dominik 'Rathann' Mierzejewski"
 
Default RPM compression format

On Friday, 20 June 2008 at 13:03, KH KH wrote:
> > I guess we also need to stage things appropriately so that those updating to
> > Fedora x (where x is the LZMA supported distro) by using on-line update
> > (yeah I know its not supported as such but its always worked well in the
> > past), are able to get the initial upgrade requirements onto their box
> > (which I guess would be rpm, yum & fedora-release) without being stymied by
> > an rpm for those packages being compressed with LZMA when their own rpm
> > cannot cope with it...
> >
> > Nigel.
>
> I think that's already done, on transaction, rpm (yum and co.) always
> search for updated version of themselves first.

I've never heard of such behaviour. Is that a fact?

> Well, indeed, rpm compressed with lzma aren't compatible with Fedora yet.
> Maybe that's the point we need to fix. Because we cannot install rpm
> from SuSE on Fedora (even if that doesn't really make sense unless for
> pure contents and we can always package it for Fedora ).
> If download size matter, I think it would be better to answear with
> deltarpms instead.
> Now maybe we can split the question of the lzma "support" in rpm
> itself with the question to "use" lzma in rpm, distro wide.

Indeed, it would make sense to first introduce support for LZMA
and then, once that's in place, switch to actually using it to
compress rpms' contents.

Regards,
R.

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Old 06-20-2008, 02:10 PM
Jeremy Katz
 
Default RPM compression format

On Fri, 2008-06-20 at 08:47 +0100, Nigel Metheringham wrote:
> On 20 Jun 2008, at 07:47, Jindrich Novy wrote:
> > The exact timing for the new rpm release is not clear yet, but there
> > would be a need of mass rebuild to fully take advantage of the new
> > compression.
>
> I guess we also need to stage things appropriately so that those
> updating to Fedora x (where x is the LZMA supported distro) by using
> on-line update (yeah I know its not supported as such but its always
> worked well in the past), are able to get the initial upgrade
> requirements onto their box (which I guess would be rpm, yum & fedora-
> release) without being stymied by an rpm for those packages being
> compressed with LZMA when their own rpm cannot cope with it...

This is why upgrades via anaconda[1] are the recommended method. The
anaconda environment then has the newer bits and things can Just Work
(tm) without requiring weird jumping through hoops

Jeremy

[1] With or without preupgrade

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Old 06-20-2008, 02:11 PM
Jeremy Katz
 
Default RPM compression format

On Fri, 2008-06-20 at 13:03 +0200, KH KH wrote:
> I think that's already done, on transaction, rpm (yum and co.) always
> search for updated version of themselves first.

No, this doesn't happen. And it gets you into a bit of a pickle because
what happens when you need the new python which needs the new glibc,
etc. ...

Jeremy

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