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I ran into an issue with a Synology RS1221+ where the NAS would boot normally with seven drives installed, but when the eighth drive was installed, the unit would power on and then shut itself down right as the drives started spinning up.

After troubleshooting, the issue appeared to be related to drive spin-up current. Large-capacity Seagate drives, especially Exos-class drives, can draw a high amount of current during startup. With all eight drives spinning up at the same time, the RS1221+ may not have enough startup power headroom, causing the system to shut down.

Symptoms

• Synology RS1221+ powers on normally with seven drives installed.
• Adding the eighth drive causes the unit to power on and then shut off during drive spin-up.
• No obvious DSM error is shown because the system shuts down before fully booting.
• The issue can look like a bad drive, bad bay, weak PSU, or backplane problem.

Likely Cause

The likely cause is startup inrush current from all eight drives spinning up at once. This is especially common with larger 7200 RPM Seagate drives. The fix was to use Seagate OpenSeaChest tools to enable low-current spin-up on the drives.

Environment Used

• NAS: Synology RS1221+
• Drives: Seagate SATA drives
• Tool: Seagate OpenSeaChest Linux x86_64 portable package
• Access: SSH as root

Step 1: SSH into the Synology

SSH into the Synology NAS, then become root:

sudo -i

Step 2: Download OpenSeaChest

The RS1221+ uses an x86_64 CPU, so download the Linux x86_64 portable version of OpenSeaChest.

cd /tmp
mkdir -p openseachest
cd openseachest

wget -O openSeaChest.tar.xz https://github.com/Seagate/openSeaChest/releases/download/v26.03.0/openSeaChest-v26.03.0-linux-x86_64-portable.tar.xz

Step 3: Extract the Tools

tar -xf openSeaChest.tar.xz
cd openSeaChest-v26.03.0-linux-x86_64-portable

Step 4: Make the Tools Executable

When trying to run the tool, you may receive this error:

-ash: ./openSeaChest_Basics: Permission denied

To fix it, make the binaries executable:

chmod +x openSeaChest_Basics openSeaChest_Configure

Then run the scan:

./openSeaChest_Basics --scan --onlySeagate

Step 5: If /tmp Is Mounted noexec

On some Synology systems, /tmp may be mounted with noexec, which prevents binaries from running from that location.

If you still get a permission error after running chmod +x, copy the tools to /root and run them from there:

mkdir -p /root/openseachest
cp -a /tmp/openseachest/openSeaChest-v26.03.0-linux-x86_64-portable/* /root/openseachest/
cd /root/openseachest

chmod +x openSeaChest_Basics openSeaChest_Configure
./openSeaChest_Basics --scan --onlySeagate

Step 6: Enable Ultra Low-Current Spin-Up

Once the Seagate drives are detected, enable ultra low-current spin-up on all detected Seagate drives:

for d in $(./openSeaChest_Basics --scan --onlySeagate | grep -o "/dev/sg[0-9]*" | sort -u); do
  echo "Setting ultra low-current spin-up on $d"
  ./openSeaChest_Configure --device "$d" --lowCurrentSpinup ultra
done

Step 7: Fully Power Off the NAS

After the setting has been applied, fully power off the NAS:

poweroff

Wait about 30 seconds, then power the NAS back on with all eight drives installed.

Final Result

After enabling ultra low-current spin-up and fully powering off the NAS, the RS1221+ was able to boot with all eight drives installed.

Rollback Command

If you need to disable low-current spin-up later, run:

for d in $(./openSeaChest_Basics --scan --onlySeagate | grep -o "/dev/sg[0-9]*" | sort -u); do
  echo "Disabling low-current spin-up on $d"
  ./openSeaChest_Configure --device "$d" --lowCurrentSpinup disable
done

Optional: PUIS

Some guides also recommend enabling PUIS, which stands for Power-Up In Standby. This can help prevent all drives from spinning up at once, but it is more aggressive and may cause drives to not appear if the controller does not properly wake them.

Because of that, I recommend trying low-current spin-up first. Only use PUIS if low-current spin-up does not resolve the issue.

To enable PUIS:

for d in $(./openSeaChest_Basics --scan --onlySeagate | grep -o "/dev/sg[0-9]*" | sort -u); do
  echo "Enabling PUIS on $d"
  ./openSeaChest_Configure --device "$d" --puisFeature enable
done

To disable PUIS:

for d in $(./openSeaChest_Basics --scan --onlySeagate | grep -o "/dev/sg[0-9]*" | sort -u); do
  echo "Disabling PUIS on $d"
  ./openSeaChest_Configure --device "$d" --puisFeature disable
done

Notes

• This fix is intended for Seagate SATA drives that support low-current spin-up.
• Always confirm drive paths before running commands.
• Do not repeatedly power-cycle the NAS while troubleshooting, especially if the RAID array contains important data.
• If the NAS still shuts down after applying this fix, the power supply may be weak or failing.
• If one specific drive causes the shutdown by itself, that drive may be faulty.
• If one specific bay causes the shutdown regardless of drive, the backplane or bay may be faulty.

Summary

If a Synology RS1221+ boots with seven drives but shuts down when the eighth drive is installed, the issue may be caused by high startup current from all eight drives spinning up at the same time. Enabling Seagate ultra low-current spin-up using OpenSeaChest can reduce the startup load and allow the NAS to boot normally with all eight drives installed.