I have two clusters set up with dedicated master nodes and data nodes. With cluster A running in one data center and cluster B running in another data center. There is NAS storage mounted to the master and data nodes that will be used as the backing store for the snapshot/restore process.
From what I understand, during the snapshot/restore process, the master nodes create/read/write the metadata- and snapshot- files and the data nodes create/read/write the index files.
My question is, do the data nodes ever read/write anything to/from the metadata- and snapshot- files either during the snapshot or restore process? Or, are those metadata- files only read/written to by the master nodes?
I ask, because I have a need to provide encryption of the index files at rest due to the nature of the data stored in the cluster. I am ultimately wondering if I can apply the encryption only to the files written by the data nodes or whether I will need to use the same encryption techniques on the master nodes as well so that the data nodes can read the metadata- and snapshot- files.