Originally Posted by fear_matrix
I have a second machine and in that server i was able to install magento and its dependecies without any issues using YUM. I have compared the default repo file in both the machine and everything is same.
Nope. Not the same: maybe in your second machine you don't have the exclude list in yum.conf. What's the deal with it? Couldn't you edit the /etc/yum.conf and comment out the exclude option? Looking at the output you posted above:
[~]# yum install php-xml
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirror.symnds.com
* extras: centos.mirror.choopa.net
* updates: mirror.ash.fastserv.com
Excluding Packages in global exclude list
Setting up Install Process
No package php-xml available.
Nothing to do
Please notice the part highlighted in red: that is the only and unique reason
why you cannot install the php packages from the CentOS repositories. In /etc/yum.conf you have:
exclude=apache* bind-chroot courier* dovecot* exim* filesystem httpd* mod_ssl* mysql* nsd* perl* php* proftpd* pure-ftpd* ruby* spamassassin* squirrelmail*
Regarding the third-party repository I agree with deep27ak: it's safe to not install so many untrusted repos, since they may bring to conflicts among different packages or different releases of the same package providing the same files. In this case it would be advisable to install the yum priorities plugin, by which you can assign a higher priority to the official repository and a lower priority to the untrusted ones. Take a look at http://wiki.centos.org/PackageManagement/Yum/Priorities
for more details.