Many people have upgraded to My Cloud OS5, only to discover that it’s not suitable for their needs. WD claims that OS5 can’t be reverted, but that’s simply not true.
The “Safe Mode” firmware appears to be unchanged by OS5, so reverting back to OS3 can be accomplished by deleting the Linux kernel and system configuration files to trigger “Safe Mode” after rebooting the NAS. Deleting the Linux kernel may sound scary, but it’s exactly what the firmware does to trigger “Safe Mode” if it detects a problem.
An SSH connection is required, and this specific process of reverting back to OS3 only works on the PR4100 and PR2100. It should NOT be attempted on any other NAS model. I’ve personally tested it on the PR4100, but I don’t use the cloud-based services, so I don’t know how they might be affected.
USE AT YOUR OWN RISK.
The processs of reverting back to OS3 causes all users except “admin” to be lost, in addition to all system settings. Shares and data should remain unaffected. If the OS3 system configuration settings were saved to a file prior to upgrading to OS5, it should be possible to restore them via the dashboard.
Settings / Utilities / System Configuration / Import File
Create backups of your data, enable SSH access from the dashboard, then shut down the NAS and remove all hard drives, being certain to label each drive so it can be reinserted in the same bay it came from. This done as a precaution, where the drives can be reintegrated afterwards, with no data loss.
Download the My Cloud OS3 firmware for your NAS from the WD website, and save it to your computer. Be certain to verify that you have the correct My Cloud OS3 firmware bin file before proceeding.
Power on the NAS, then connect via SSH and log in (user: sshd) to get a Linux command prompt. An SSH client such as Putty is required. Execute the following commands, which will erase the Linux kernel and system settings, thus triggering the “Safe Mode” after a reboot, where new firmware may be uploaded. The commands must be executed ONE LINE AT A TIME , not all at once.
Erase Linux kernel:
mkdir /tmp/wdnas_kernel
mount /dev/mmcblk0p2 /tmp/wdnas_kernel
rm -f /tmp/wdnas_kernel/uImage
Erase Config Files and Backups:
rm -rf /usr/local/tmp_wdnas_config/*
mkdir /tmp/wdnas_backup
mount /dev/mmcblk0p9 /tmp/wdnas_backup
rm -rf /tmp/wdnas_backup/*
WARNING: Carefully type the commands exactly as shown above, and don’t touch /dev/mmcblk0p1 or /dev/mmcblk0p5. The following is is a list of the eMMC partitions, for reference only.
/dev/mmcblk0p1 "wdnas_efi"
/dev/mmcblk0p2 "wdnas_kernel"
/dev/mmcblk0p3 "wdnas_initramfs"
/dev/mmcblk0p4 "wdnas_image.cfs"
/dev/mmcblk0p5 "wdnas_rescue_fw"
/dev/mmcblk0p6 "wdnas_config"
/dev/mmcblk0p7 "wdnas_reserve1" (hidden)
/dev/mmcblk0p8 "wdnas_reserve2" (hidden)
/dev/mmcblk0p9 "wdnas_backup"
Simply power off the NAS, then power it on again, giving it time to finish booting into “Safe Mode”. Afterwards, connect to it via a web browser using the IP address. A “Safe Mode” firmware upload page should become available, where you can manually upload the OS3 firmware, as appropriate for your NAS.
WARNING: If you assigned a static IP address using the NAS, it won’t work because it was erased when the config files were deleted as part of the reversion process. The NAS will be assigned a new IP address by the router via DHCP. Log into the router and determine what the new IP address is, then use that to connect to the NAS with a browser. If you have trouble uploading new firmware, try a different browser.
After uploading the OS3 firmware, and the NAS has finished rebooting, power it off again and reinsert the hard drives. Power on the NAS, where all installed hard drives should now have a red status light after the boot process has finished. Connect to the dashboard via a web browser using the IP address and a “RAID Roaming” message should appear after logging in. Click “OK” to integrate the hard drives, without data loss. Afterwards, the status light for each installed hard drive should turn blue.
The process is now complete.
