Restoring a Backup from a SAS Metadata Cluster

This tip explains how to recover a Metadata Server from an environment that contains a SAS Metadata Cluster.

Performing a metadata backup in a clustered metadata server environment is no different than performing a metadata backup in a non-clustered environment. However, recovering a Metadata server from a backup is slightly different within a clustered environment. It is not possible to restore a SAS Metadata backup whilst multiple metadata nodes are running in a cluster. An administrator needs to recover just one node within the cluster. The remaining nodes are then updated with the recovered metadata. In order to successfully recover from a backup, a single Metadata Server needs to be running without clustering.

1.1 Starting a Single Node without Clustering

Before an administrator can start a single node without clustering, the SAS administrator should stop any SAS services which are dependent upon the Metadata Server service. Once this is done, the Metadata Cluster server itself needs to be stopped. This can be achieved as follows:

1. Navigate to the SAS Metadata Server configuration directory (it does not matter if the platform uses a shared configuration directory, any Metadata Node will do):

   <SAS-Config-Directory>/SASMeta/MetadataServer/

2. Within this directory, run the following command:

All Metadata Services will be stopped. Once it is confirmed that all Metadata services are stopped, the Metadata Server needs to be started without clustering. This can be done in the same directory, using the following command:

1.2 Restoring/Recovering Metadata

Once a single Metadata Node is running without clustering, Metadata can be recovered from a backup as follows:

1. Log on to SAS Management Console. A message will be displayed explaining that the server is paused for administration. This is expected.
2. Within the “Plug-Ins tab”, expand “Metadata Manager”, “Metadata Utilities” and then click on “Server Backup”:

3. Right-click on your desired backup, select “Recover from this backup” and enter appropriate comments for the backup history.

1.3 Starting the Metadata Cluster

Once the recovery has been completed successfully, the Metadata cluster needs to be started once again. This can done by:

1. Restarting (or stopping and starting) the current node to place it in the cluster as the “Master Node”;
2. Starting the Metadata Service on all other nodes. The Master Node will update the metadata on all the new nodes, using the data from the restored backup.
3. Once the Metadata cluster has reached quorum, the remaining SAS services can then be started across the platform.

It is possible to view the status of a Metadata cluster by:

1. Expanding the “Metadata Manager” within the “Plug-Ins” tab in SAS Management Console
2. Right-clicking on “Active Server” and select the “Cluster” tab.

The first node started should be listed as the “Master”. “State: QUORUM” will be displayed once the Metadata cluster has reached quorum.