Where the work happens.
WHAT HARDWARE RAID IS
A dedicated controller managing the array.
WHAT IT PROVIDES
Offloading from the processor Battery or capacitor-backed write caching Presentation as a single device
WHAT WRITE CACHING PROVIDES
Substantially faster writes, acknowledged before reaching the drive.
WHAT PROTECTS IT
A battery or capacitor, so the cache survives power loss.
WHAT TO VERIFY
That the battery is healthy.
WHY
A failed battery disables write caching, and performance collapses without warning.
WHAT HARDWARE RAID RISKS
Dependence on the controller, since arrays may not be readable by a different model.
WHAT TO KEEP
A spare compatible controller, for critical systems.
WHAT SOFTWARE RAID PROVIDES
No controller dependence Arrays readable on any system with the same software Visibility into every drive
WHAT MODERN FILE SYSTEMS ADD
Integrated volume management with checksums, detecting silent corruption.
WHY THAT MATTERS
Traditional arrays cannot tell which copy is correct when they differ.
WHAT TO MONITOR EITHER WAY
Array status, drive health indicators, and rebuild progress.
WHAT TO TEST
Removing a drive deliberately, and rebuilding.
