Hello @rootuser,
Thanks for using Cloudera Community. Based on the Post, You are trying to use CopyTable to copy HBase Table(s) from 1 Cluster to another Cluster, wherein 1 Mapper is being observed.
Please confirm if the Source Table has 1 Region only. Additionally, Confirm if CopyTable on a Table with >1 Regions (Say, 5 Regions) creates 1 Mapper or 5 Mappers. Also, Please state the HBase Version being used by your Team. Additionally, Share the Timeout being observed by your Team.
As far as I recall, HBase uses 1 Mapper per Region. As such, It's likely the Source Table has 1 Region only. In such case, Increasing the Region Split by Pre-Split or Increasing the Timeout should help.
Regards, Smarak