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Chapter 3. Container-Ready Storage for OpenShift Container Platform
Container-Ready Storage is deployed as a stand-alone Red Hat Gluster Storage cluster that provides persistent storage to containers, unlike Container-Native Storage, which is deployed on top of an OpenShift Cluster.
Container-Ready Storage provides the same storage functionality to OpenShift Container Platform as Container-Native Storage. Container-Ready Storage provides dynamic provisioned storage, statically provisioned storage, RWO support, and RWX support. Further, it provides full support for OpenShift Container Platform infrastructure services like logging, metrics, and registry services. Being stand-alone of OpenShift Container Platform, Container-Ready Storage does have an advantage regarding providing additional Red Hat Gluster Storage data services functionality to what is supported by OpenShift, such as, Snapshot, Geo Replication, and Nagios Monitoring.
For users of persistent storage, the deployment modes are completely transparent. Administrators will see variation in how they set the system up, manage, and scale. In Container-Ready Storage, storage is managed like Red Hat Gluster Storage.
Following are some of the key drivers of choosing Container-Ready Storage mode of deployment:
- OpenShift Container Platform administrators might not want to manage storage. Container-Ready Storage separates storage management from container management.
- Leverage legacy storage (SAN, Arrays, Old filers): Customers often have storage arrays from traditional storage vendors that have either limited or no support for OpenShift. Container-Ready Storage mode allows users to leverage existing legacy storage for OpenShift Containers.
- Cost effective: In environments where costs related to new infrastructure is a challenge, they can re-purpose their existing storage arrays to back OpenShift under Container-Ready Storage. Container-Ready Storage is perfect for such situations where one can run Red Hat Gluster Storage inside a VM and serve out LUNs or disks from these storage arrays to OpenShift offering all of the features that the OpenShift storage subsystem has to offer including dynamic provisioning. This is a very useful solution in those environments with potential infrastructure additions.
Container-Ready Storage may have Heketi, and other provisioners (components of Container-Ready Storage) deployed on top of OpenShift Cluster nodes. With Container-Native Storage 3.6, Red Hat recommends Heketi be deployed on OpenShift Cluster. Heketi is a service endpoint for automated Red Hat Gluster Storage volume provisioning, where requests for allocation of Red Hat Gluster Storage volumes to back OpenShift PVs land from kubernetes. Heketi manages allocation and de-allocation of Red Hat Gluster Storage volumes dynamically.