Is there any way to track/audit delete operations per volume ?
Here is some information on the MapR Auditing feature. If you are running version 4.1 or earlier, you will need to upgrade and enable the feature.
Auditing Cluster Activity
The auditing of cluster administration keeps a record of all MCS, maprcli, and REST calls - which would cover most of the volume operations. You can also enable a deeper level of auditing at the file, directory, and table level (if you want to audit what is happening with specific entities within volumes).
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