Enable cgroup-based resource management
If you want to use cgroups, you must enable cgroup-based resource management. You can enable it for all hosts, or on a per-host basis.
Using cgroups-based resource management, has the following limitations:
- Role group and role instance override cgroup-based resource management parameters must be saved one at a time. Otherwise some of the changes that should be reflected dynamically will be ignored.
- The role group abstraction is an imperfect fit for resource management parameters, where the goal is often to take a numeric value for a host resource and distribute it amongst running roles. The role group represents a "horizontal" slice: the same role across a set of hosts. However, the cluster is often viewed in terms of "vertical" slices, each being a combination of worker roles (such as TaskTracker, DataNode, RegionServer, Impala Daemon, and so on). Nothing in Cloudera Manager guarantees that these disparate horizontal slices are "aligned" (meaning, that the role assignment is identical across hosts). If they are unaligned, some of the role group values will be incorrect on unaligned hosts. For example a host whose role groups have been configured with memory limits but that's missing a role will probably have unassigned memory.
- In Cloudera Manager, click the Host tab.
- Find the host in which you want to enable cgroups.
- Click the Configuration tab.
- Search for cgroups.
- Find Enable Cgroup-based Resource Management and select it.
- Restart all roles on the host or hosts.