### [Document URL]
1. https://docs.openshift.com/container-platform/4.7/logging/config/cluster-logging-log-store.html#cluster-logging-elasticsearch-storage_cluster-logging-store
2. https://docs.openshift.com/container-platform/4.7/scalability_and_performance/optimizing-storage.html

### Section Number and Name: 
For 1. It's "configuring persistent storage for the log store"

For 2. It's mentioned several time across several sections.

### [Describe the issue]

It's not clear what the documentation is saying about is NFS is supported or not with Logging in two different parts of the OpenShift documentation. Let's try to explain:

In the Logging documentation in section [Configuring persistent storage for the log store](https://docs.openshift.com/container-platform/4.7/logging/config/cluster-logging-log-store.html#cluster-logging-elasticsearch-storage_cluster-logging-store) it's clear that it's not supported with these words:

"Using NFS storage as a volume or a persistent volume (or via NAS such as Gluster) is not supported for Elasticsearch storage, as Lucene relies on file system behavior that NFS does not supply. Data corruption and other problems can occur."

If we  check the words about this in the Scalability and performance - [Optimizing storage](https://docs.openshift.com/container-platform/4.7/scalability_and_performance/optimizing-storage.html) in:

1. [Matrix](https://docs.openshift.com/container-platform/4.7/scalability_and_performance/optimizing-storage.html#recommended-configurable-storage-technology_persistent-storage) says that it's not recommended, but yes Configurable
2. [Specific application storage recommendations](https://docs.openshift.com/container-platform/4.7/scalability_and_performance/optimizing-storage.html#specific-application-storage-recommendations) says:

"Testing shows issues with using the NFS server on Red Hat Enterprise Linux (RHEL) as storage backend for core services. This includes the OpenShift Container Registry and Quay, Prometheus for monitoring storage, and Elasticsearch for logging storage. Therefore, using RHEL NFS to back PVs used by core services is not recommended.

Other NFS implementations on the marketplace might not have these issues. Contact the individual NFS implementation vendor for more information on any testing that was possibly completed against these OpenShift Container Platform core components."

In summary, in:

    Logging documentation in section [Configuring persistent storage for the log store](https://docs.openshift.com/container-platform/4.7/logging/config/cluster-logging-log-store.html#cluster-logging-elasticsearch-storage_cluster-logging-store) we say that not supported
    [Optimizing storage](https://docs.openshift.com/container-platform/4.7/scalability_and_performance/optimizing-storage.html) we are saying that it's not recommended, but we are "allowing" to use NFS and it's "configurable"

Then, this should be fixed to reflect the best and not being contradictory to this information.

### [Suggestions for improvement]
Not sure, but probably, in:

  - [Optimizing storage](https://docs.openshift.com/container-platform/4.7/scalability_and_performance/optimizing-storage.html)

should be deleted all the mentions to Logging and leave only the documentation in:

  -  [Configuring persistent storage for the log store](https://docs.openshift.com/container-platform/4.7/logging/config/cluster-logging-log-store.html#cluster-logging-elasticsearch-storage_cluster-logging-store) 

saying that it's not supported.

Or, it's desired to leave the mentions in:

  - https://docs.openshift.com/container-platform/4.7/logging/config/cluster-logging-log-store.html#cluster-logging-elasticsearch-storage_cluster-logging-store

Then in   - [Optimizing storage](https://docs.openshift.com/container-platform/4.7/scalability_and_performance/optimizing-storage.html)

Only leave a reference to the Scalability section for verifying the storage needed. 

Duplicate the information as it's now, it leads to get opposite information from different places of the documentation.

Additional information: