Does Percona Xtrabackup support RedHat release 4
Percona XtraBackup 2.2 does not seem to have support out of the box for Red Hat 4:


  Supported Releases
  
  The CentOS repositories should work well with Red Hat Enterprise Linux
  too, provided that yum is installed on the server.

CentOS 5 and RHEL 5
CentOS 6 and RHEL 6
CentOS 7 and RHEL 7
Amazon Linux AMI (works the same as CentOS 5)



Try, however, first the generic Linux binary and see if you can at least run the xtrabackup binary.

If not, you can either try to compile it by yourself (it shouldn't be too difficult in terms of dependencies, but Xtrabackup is a monster source and you may en up in dependency hell) or hire their paying support/development so they can make it work for you (they have great engineers).