This section provides information on the various components of the Apache Hadoop ecosystem.
In many data centers, the following deployment strategy may be optimal:
Use a mirror for the HDP Repositories. The HDP Repositories are small and easily mirrored, thereby allowing secure control over the contents of the Hadoop packages accepted for use in your data center.
Use a caching proxy for the EPEL repository, which is a well-known and trustworthy repository managed by the Fedora Project team, and which may be too large to mirror in your data center. If your data center already mirrors or proxies EPEL, use that mirror or proxy.
![[Note]](../common/images/admon/note.png)
Note The installer pulls many packages from the base OS repositories (repos). If you do not have a complete base OS available to all your machines at the time of installation, you may run into issues. For example, if you are using RHEL 6 your hosts must be able to access the “Red Hat Enterprise Linux Server 6 Optional (RPMs)” repo. If this repo is disabled, the installation is unable to access the rubygems package, which is necessary for HMC to operate.
If you encounter problems with base OS repos being unavailable, please contact your system administrator to arrange for these additional repos to be proxied or mirrored.
