[GLLUG] Problems with CentOS 4 to 5 upgrade

chrisp chris at chrisprocter.co.uk
Sat Nov 25 09:09:36 UTC 2017

> I have pointed the Centos-Base.repo file to use the 5.11 vault.
> It has gone "by the book" so far except that I keep hitting "road
> blocks" in resolving all the dependency problems in the "yum upgrade"
> step.
> The current road block is this error:
> Error: Missing Dependency: libdmraid.so.1.0.0.rc13-17 is needed by
> package python-pyblock
> Error: Missing Dependency: libdmraid.so.1.0.0.rc13-17(Base) is needed
> by package python-pyblock
> I have previously overcome these by removing the problem module, and
> noting it so I can install it post-upgrade.
> However In this case "python-pyblock" I can find no trace of it on the
> system and "yum remove" or "rpm -e" fails to work.

Its been ages since I touched centos/rhel4  but...
You are trying to install python-pyblock, if its not on the centos4 system
then its required by something else as a dependancy and thats why its being
pulled in.

python-pyblock has a dependency on libdmraid.so.1.0.0.rc13-17 so yum is
trying to bring that in.   (the version number there is very precise which
is a bit worrying)

Yum dependencies actually deal in capabilities ("provides" and "requires"
in the rpm spec file) rather then explicit package names so there will be a
package somewhere with a "provides"  of libdmraid.so.1.0.0.rc13-17 and if
we figure out what it is and install it and python-pyblock will then
install cleanly.

A bit of messing around on my F27 laptop and then with the centos5 repos
gives me

[chrisp at radium ~]$ rpm -q --provides dmraid-1.0.0.rc13-65.el5.x86_64.rpm
dmraid = 1.0.0.rc13-65.el5

So the dmraid package provides the capability that python-pyblock depends

So the question isn't so much why is it installing python-block (at a guess
theres some sort of lvm tool or gui that uses it), and more why cant yum
resolve the libdmraid dependancy and install the dmraid package to meet it
before trying python-pyblock.
Which makes me think you're probably not using yum to do the update but are
doing it with rpm? Or possibly there is another error message hidden in the
output you've missed.

This is an example of doing major release upgrades is bad and why Red Hat
don't support it. rhel/centos4 shipped with up2date as its package manager,
rhel/centos5 moved to yum, so the tool you are relying on to do the
upgrades is changing completely as you are using it. Testing this with all
its possible combinations of packages and stupid configs to the extent that
you are able to charge for paid support with SLAs and legal obligations for
thousands of customers worldwide, and doing it in a cost effective way, is
almost impossible. Even the EL6 to EL7 "supported" upgrade has many caveats

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