SysAdmin

A practical guide to diagnosing impaired EC2 instances by detaching and reattaching EBS root volumes to a rescue instance. Covers the full workflow from stopping the impaired node to restoring it to normal service.

A quick walkthrough of using the Ranger REST API to bulk-delete existing users, including how to capture an auth cookie and loop through a user list with curl.

A troubleshooting guide for the Kerberos error ‘Cannot find key of the appropriate type to decrypt AP REP,’ covering encryption type mismatches between keytabs and Active Directory, plus practical steps to align AES and RC4 settings.

A quick reference for which JDK releases ship with Unlimited Strength JCE enabled by default, plus a small test program to verify your environment.

Learn how to verify that your file system supports hole punching by creating a test file, punching a hole with fallocate, and confirming the space savings with du.

Enabling HDFS encryption at rest adds per-file metadata overhead to the NameNode heap. This guide breaks down the memory impact and gives a practical rule of thumb for right-sizing your NameNode heap.