'disconnected' mode

[dstreev]

Allow hms-mirror run without a connection to the "RIGHT" cluster.

In this case, it will not be possible to determine the existence of db's/tables on the right. So all output will assume they don't exist (no incrementals).

Use cases:

• Schema Only Transfers
• SQL, EXPORT_IMPORT, and HYBRID only when -is or -cs is used. This might be the case when the clusters are secure (kerberized), but don't share a common kerberos domain/user auth. So an intermediate or common storage location will be used to migrate the data.
• Both clusters (and HS2 endpoints) are Kerberized, but the clusters are NOT the same major hadoop version. In this case, hms-mirror doesn't support connecting to both of these endpoints at the same time. Running in the disconnected mode will help push through with the conversion.

hms-mirror will run as normal, with the exception of examining and running scripts against the right cluster. It will be assumed that the RIGHT cluster elements do NOT exist.

The RIGHT_ 'execution' scripts and distcp commands will need to be run MANUALLY via Beeline on the RIGHT cluster.

[dstreev]

Note: This will be know as the "right-is-disconnected" option. Which means the process should be run from a node that has access to the "left" cluster. This is 'counter' to our general recommendation that the process should be run from the 'right' cluster.