[Beowulf] best linux distribution
ajt at rri.sari.ac.uk
Mon Oct 8 14:25:07 PDT 2007
Mark Hahn wrote:
>> What I like about APT (the Debian package manager) is the dependency
checking and conflict resolution capabilities of "aptitude", which is
more robust than
> I'm curious - how does a conflict happen, and how is it resolved?
> I guess that this must have to do with packages which specify
particular versions of packages they depend on, or perhaps minimal
> versions of them. but a conflict seems to imply that you'd have a
package which ultimately has conflicting dependencies.
Debian has a very large range of packages, some of which are known to
conflict a priori because they solve similar problems, but they are
maintained by different people with different objectives. Each package
maintainer has a responsibility to declare known conflicts with other
packages. However, the permutations of packages that could be combined
in an installation are also very large. APT tracks files that are used
in all packages and automatically detects conflicts. The APT conflict
resolver suggests strategies to solve problems like this, and also the
dependencies that are caused by package upgrades. It's not a new idea,
but it works very well.
This statement is in the current Debian release notes:
"2.1.1 Package management
aptitude is the preferred program for package management from console.
aptitude supports most command line operations of apt-get and has proven
to be better at dependency resolution than apt-get. If you are still
using dselect, you should switch to aptitude as the official frontend
for package management.
For etch an advanced conflict resolving mechanism has been implemented
in aptitude that will try to find the best solution if conflicts are
detected because of changes in dependencies between packages."
> how often does this happen, and is it mainly the result of
It doesn't happen very often, but when it does "aptitude" has got me out
of several deep holes... It's not because of misconfiguration. It's
because the 'topological' map of package dependencies is complex, and
not all possible interactions between all packages can be anticipated
because the search space of package combinations is extremely large.
> and resolution is simply having multiple version of some depended-on
package installed, right?
Sounds so easy, doesn't it ;-)
>> the older "apt-get". I previously ran Red Hat 5.3->9 and I've used
both "up2date" and "yum". Neither of these is as capable of resolving
package conflicts and dependencies as APT. I used APT for RPM when I ran
RH9 for exactly this reason.
> hmm, I've never had any problems with yum.
Fair enough, but I found that it placed more of the burden of package
management on me than I wanted. APT for RPM was wonderful by comparison.
I used it for several years until the Fedora Legacy Archive stopped
supporting RH9. At this point I had already been evaluating Debian on
one of our Beowulf servers, but I decided to use Ubuntu instead.
Dr. A.J.Travis, | mailto:ajt at rri.sari.ac.uk
Rowett Research Institute, | http://www.rri.sari.ac.uk/~ajt
Greenburn Road, Bucksburn, | phone:+44 (0)1224 712751
Aberdeen AB21 9SB, Scotland, UK. | fax:+44 (0)1224 716687
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