Guide for What happen to PR4100 NAS and WD Red disk?

The PR4100 runs on the older My Cloud OS and associated desktop tools, like WD Sync and Dashboard, all of which have reached End of Updates

. That means no more firmware upgrades, security patches, or improvements from WD.

Drive Reporting Errors & False Failures

Many owners report their PR4100 flagging drives as failed, despite SMART tests showing no issues:

One user found a PR4100 marking drives as "bad" with red LEDs even after swapping them out—and SMART tests all passed. Sometimes a reboot would clear the error

Western Digital

Another described how removing a "spare" in RAID 5 configuration caused the drive LED to stay red, even though everything was healthy. Reconfiguring to include a spare helped

Drive Bay or Thermal Faults

Repeated failures in the same bay seem to occur—one user had drive #1 fail twice in a few months, prompting suspicion the bay itself or firmware is at fault

Other reports suggest the PR4100 may suffer from poor thermal handling; performance and drive errors sometimes improved after manually boosting airflow with an external fan

WD Red Drives – Reliability & Risks

SMR vs. CMR Drive Confusion

Starting 2020, WD decided to use SMR technology for WD Red drives without clearly communicating it, sparking backlash since SMR is not ideal for NAS/RAID environments. In response, WD introduced the “Red Plus” line (using CMR) for NAS use, while older “WD Red” models continued to use SMR

High Incidence of Failures in Recent Batches

Across forums, many users report alarming failure rates—especially with newer, higher-capacity drives:

A Redditor with 20 TB WD Red Pro drives experienced four failures in a RAID 5 array within months. RMA delays left them with a degraded setup

Another in the WD community wrote that of 4×10 TB WD Reds, three failed in under six months—even when SMART gave no prior warning:

“...three have failed in less than six months, including two within two weeks of each other.”

Mixed Experiences—Some Drives Last Years

It's not all bleak: other users boast long-running WD Reds (e.g., >11 years), though these are typically older models and possibly not representative of modern manufacturing

Issue What You Can Do

PR4100 false drive failure flags Keep full backups. Try reboots when a drive shows red light. Consider RAID 5 + hot spare or rebuild if LEDs persist.

Potential bay/Firmware issues Avoid continuous reliance on the same bay. Test by swapping disks. External cooling may help.

Choosing drives Prefer WD Red Plus (CMR) over WD Red (SMR). If unexplained failures continue, consider alternatives like Seagate IronWolf or HGST—but always backup.

Your Summary

The WD PR4100 is aging—support is ended, and it’s showing clear signs of both hardware and firmware fragility, including creating false drive failure alarms. At the same time, the reliability of WD Red drives has become inconsistent, particularly newer high‑capacity models and especially SMR-based variants. Many users have shifted to Red Plus or even switched brands after repeated damage or RMA hassles.