Prevent HDD spin-down / keep disk always active

[inlinecoder]

Hi,

First of all, great work on this project — getting SMB running on Time Capsule hardware is impressive.

I’m considering repurposing a Time Capsule as a lightweight always-on SMB device with a larger NAS-grade HDD (8–12TB), and I have a question regarding disk power management.

Is it possible (or already supported) to prevent the internal HDD from spinning down?

My goal is:

• Keep the disk always spinning (no sleep / no standby)
• Avoid latency when accessing files over SMB
• Use a NAS-grade drive designed for 24/7 operation

From what I understand, spin-down behavior could be controlled by:

• macOS / underlying system power management
• disk firmware (APM / AAM settings)
• or low-level utilities (e.g., hdparm-like controls, if available)

Questions:

1. Does this firmware expose any control over disk sleep/spin-down?
2. Is there a way to disable it via config, launchd, or system tweaks?
3. If not, would this be feasible to implement?
4. Are there hardware or thermal constraints that would make this unsafe?

I’m fine with higher power usage and wear — the priority is consistent availability and responsiveness.

Thanks.

[hbokh]

2. Is there a way to disable it via config, launchd, or system tweaks?

A practical option is to modify drive settings via SSH, using the atactl command.

atactl rwd0 setidle 0
atactl rwd0 setstandby 0

atactl wd0 checkpower
Current power status: Active mode

The r in de disk name is the raw device path.