Hi Dear.
I use oracle virtualbox and install red hat Linux 6 . i configure yum server. but my yum server cannot working .
Loaded plugins: refresh-packagekit, rhnplugin
This system is not registered with RHN.
RHN support will be disabled.
file:///home/server/Packages/repodata/repomd.xml: [Errno 14] Could not open/read file:///home/server/Packages/repodata/repomd.xml
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: server. Please verify its path and try again
[root@abho Packages]#


please help me..how can solve the problem ?

you HAVE !!! to buy the required redhat support contract to get updates and to install software

there are NO!!! " if's and's or but's " on this

the standard 1 year server license is $799/year USD
the standard 1 year Desktop install license is $299 / year

also rhel 6 is starting to show it's old age
unless you MUST USE RHEL 6.7 ( the current )

install the current RHEL 7.2


so

buy the required support contract or do not use rhel and instead install one of the FREE clones
CentOS 6.7 or 7.2
Scientificlinux 6.7 or 7.2

Simple..you buy the license, and register your system with Red Hat. It says, VERY clearly, "This system is not registered with RHN"....if you tried putting that into Google, it would pull up, as the VERY FIRST HIT:
https://access.redhat.com/solutions/8036

...instructions on how to do it. And unless you NEED RHEL, then don't use it...CentOS is identical, but free. And the latest version is 7.x, so loading 6 is a bad idea to start with.