SysAdmin

A quick reference for enabling verbose Kerberos and Hadoop debug output on the command line, so you can see exactly where authentication is failing.

A practical walkthrough of how Hadoop maps Kerberos principals to short names via the auth_to_local property, including rule syntax, acceptance filters, and common troubleshooting patterns.

A quick guide to diagnosing and resolving the ‘Key has been revoked’ error in the Linux kernel keyring using keyctl commands.

Pipe the mount command through column -t to get a clean, aligned table of all mounted filesystems. A quick sysadmin trick for scanning devices, mount points, and options at a glance.

A quick reference for querying MySQL information_schema to list all foreign key constraints in a given database, including the referencing and referenced columns.

Adjusting the NameNode trash checkpoint interval can resolve TGT renewal issues on non-HA NameNodes using KMS. This change is safe and does not affect trash retention.