Win+Debian: Beszel-agent keeps external hard drives awake

[ghhorschte]

I have two NAS systems—one NUC running Debian and another running Windows 11. Each is connected to three external USB hard drives (WD Elements).
I’ve observed that when the Beszel agent is running, the hard drives no longer go into sleep mode because the agent keeps them awake.
I don’t want to disable S.M.A.R.T. monitoring entirely, as I need to keep track of those values.
I’ve experimented with several parameters—such as DISK_USAGE_CACHE and EXTRA_FILESYSTEMS—as well as EXCLUDE_SMART (though, again, I don’t want to disable it completely), but without any real success; the drives remain active.

What is the recommended approach for my setup on Win AND Debian?

• I want to avoid the external drives being constantly woken up; having them wake up just once a day to cache the data would be acceptable.

[svenvg93]

SMART collection already tries not to wake sleeping disks. Every smartctl call uses -n standby. If a disk is asleep, the agent skips it and keeps showing the last reading. The only time it wakes a disk on purpose is once after the agent starts, so it has an initial reading. Disk I/O stats come from kernel counters and never touch the drive.

My guess is that the WD Elements USB enclosures are the problem. Many USB-SATA bridges don't pass the "check power mode" command through to the disk. They either always answer "active", or the check itself spins the disk up. Then -n standby can't help, and the scheduled SMART read wakes the drive (once an hour by default).

What I'd suggest, on both machines:

1. Update the agent to the latest version. The standby handling was reworked recently.

2. Set SMART_INTERVAL=24h on the agent. That gives you the "wake once a day" you mentioned, without turning SMART off. Also avoid the manual SMART refresh button for these systems, because it reads the drives right away.

3. Leave the drives out of EXTRA_FILESYSTEMS if you don't need their disk usage charts. If you do need them, add DISK_USAGE_CACHE=1h (or longer). That setting only affects drives listed in EXTRA_FILESYSTEMS.

4. Check whether standby detection works by setting LOG_LEVEL=debug. While a drive is spun down, look for smartctl reports device in standby, skipping in the agent log.

   • If you see it, SMART is leaving the drive alone and something else is waking it.
   • If you never see it, the enclosure is hiding the sleep state. In that case point 2 is the real fix.

   You can also test this without Beszel. Let a drive spin down, then run:

   smartctl -n standby -i /dev/sdX
   

If you try this, please post what the debug log shows. Then we can tell whether it's the enclosure or something in the agent.

[ghhorschte]

I forgot to mention an important point, sorry. On my Windows system, I also set LHM=true because the WMI CPU temperature readings weren't accurate.
Is LHM the culprit on Windows that keeps the disks from spinning down—and how can this be avoided?

[svenvg93]

I don't use Windows myself, so I can't say anything useful about LHM. Maybe someone running Beszel on Windows can chime in. A quick test would be to temporarily remove LHM=true and see whether the drives spin down.

[ghhorschte]

Thanks for the tips. Yes, the settings for Linux work; the disks remain inactive.
On Windows, the issue lies with LHM :-(
Unfortunately, I cannot configure Beszel to skip disk scanning (which is possible in the native LHM.exe via File -> Hardware -> Storage Devices).

I cloned the repository and set IsStorageEnabled = false in ./agent/lhm/beszel_lhm.cs:
var computer = new Computer
{
IsCpuEnabled = true,
IsGpuEnabled = true,
IsMemoryEnabled = true,
IsMotherboardEnabled = true,
IsStorageEnabled = false, <-- FALSE
// IsPsuEnabled = true,
// IsNetworkEnabled = true,
};

I built the agent myself, but the disks are still active; I’m not sure if my change was actually applied or if this flag has the intended effect.
It would certainly be better if this could be configured via an environment variable.

[ghhorschte]

Temporary solved:
I took a closer look at the code. I successfully built beszel_lhm.exe with IsStorageEnabled = false.
The issue:
beszel_lhm.exe is installed/extracted once—in my case, to C:\Windows\SystemTemp\beszel—and is not updated upon subsequent launches.
I deleted the file, placed my own version of the .exe there, and—voilà—the external disk no longer wakes up, yet I still have full access to data such as LHM CPU temperatures.

So, if I could make a request (it’s almost Christmas, after all ;o)), could you please add an environment variable to control this setting in
./agent/lhm/beszel_lhm.cs

var computer = new Computer
{
// ...
IsStorageEnabled = ENV_LHM_IS_STORAGE_ENABLED
};