Advantages of Parcels
Because of their unique properties, parcels offer the following advantages over packages:
- Distribution of CDH as a single object - Instead of having a separate package for each component of CDH, parcels are distributed as a single object. This makes it easier to distribute software to a cluster that is not connected to the Internet.
- Internal consistency - All CDH components are matched, eliminating the possibility of installing components from different CDH versions.
Installation outside of
/usr- In some environments, Hadoop administrators do not have privileges to install system packages. With parcels, administrators can install to
/opt, or anywhere else.
Installation of CDH without
sudo- Parcel installation is handled by the Cloudera Manager Agent running as
rootor another user, so you can install CDH without
- Decoupled distribution from activation - With side-by-side install capabilities, you can stage a new version of CDH across the cluster before switching to it. This allows the most time-consuming part of an upgrade to be done ahead of time without affecting cluster operations, thereby reducing downtime.
- Rolling upgrades - Using packages requires you to shut down the old process, upgrade the package, and then start the new process. Errors can be difficult to recover from, and upgrading requires extensive integration with the package management system to function seamlessly. With parcels, when a new version is staged side-by-side, you can switch to a new minor version by simply changing which version of CDH is used when restarting each process. You can then perform upgrades with rolling restarts, in which service roles are restarted in the correct order to switch to the new version with minimal service interruption. Your cluster can continue to run on the existing installed components while you stage a new version across your cluster, without impacting your current operations. Major version upgrades (for example, CDH 5 to CDH 6) require full service restarts because of substantial changes between the versions. Finally, you can upgrade individual parcels or multiple parcels at the same time.
- Upgrade management - Cloudera Manager manages all the steps in a CDH version upgrade. With packages, Cloudera Manager only helps with initial installation.
- Additional components - Parcels are not limited to CDH. Add-on service parcels are also available.
- Compatibility with other distribution tools - Cloudera Manager works with other tools you use for download and distribution, such as Puppet. Or, you can download the parcel to Cloudera Manager Server manually if your cluster has no Internet connectivity and then have Cloudera Manager distribute the parcel to the cluster.