I had the exact same problem couple of days back on RHEL5.8 , It was because I was not able to connect to the http site from my site, it was blocked,
So I had to work with the network guys, to allow my id to access it, or you can try to manually get it(wget worked for me) and bring it into your yum repo. and then re-try the cmd
The above worked for me.
yum install epel-release cmd issue
I am using AMI centos-6.3-server (ami-e585118c) on EC2 for HDP 1.3 , getting following error while running following command "yum install epel-release" .
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirror.solarvps.com
* extras: mirror.itc.virginia.edu
* updates: mirror.cogentco.com
HDP-UTILS-220.127.116.11/primary_db | 35 kB 00:00
http://public-repo-1.hortonworks.com/HDP-UTILS-18.104.22.168/repos/centos6/repodata/3ce9995aeeed2a01728c3a29b10ba1d9bd1a8fa4da59add18c5a079b2df3a2ce-primary.sqlite.bz2: [Errno -3] Error performing checksum
Trying other mirror.
Error: failure: repodata/3ce9995aeeed2a01728c3a29b10ba1d9bd1a8fa4da59add18c5a079b2df3a2ce-primary.sqlite.bz2 from HDP-UTILS-22.214.171.124: [Errno 256] No more mirrors to try.
Thanks in Advance,