Shutdown Issues on NetBSD 10.0/amd64 with USB Boot Device

[Matthias Petermann <mp%petermann-it.de@localhost>]

Hello,

I am encountering a shutdown issue on a NAS system running NetBSD 
10.0/amd64. This system includes four SATA drives for storage and an 
internal USB port used for booting the OS. Here is a brief overview of 
my setup and the problem:

# System Setup

- Storage: Four SATA drives.
- Boot Device: Internal USB port with a memory stick containing NetBSD 
10.0 boot loader and root filesystem
- Filesystem: FFSv2ea with WAPBL enabled for the root filesystem.

The installation and initial operation work without issues. The system 
boots and functions as expected. However, I encounter a significant 
problem when attempting to shut down or reboot the system.

# Problem Description

When issuing a shutdown or reboot command, the system does not complete 
the process. Even on a vanilla installation (with only the root 
filesystem mounted), the system hangs during shutdown, which is 
particularly problematic for remote operation.

# Details

- The system runs from a memory stick attached as sd0.
- dk1 wedge contains a small swap partition.
- dk0 wedge contains the root filesystem.

When executing the shutdown command:

```
shutdown -p now
```

the system proceeds with the shutdown process but hangs at the final 
stage when the kernel detaches its ressources with the following messages:

```
[ xxx.xxxxxx ] dk1: detached
[ xxx.xxxxxx ] sd0(umass0:0:0:0): generic HBA error
[ xxx.xxxxxx ] sd0d: error writing fsbd 25673345 (sd0 bn 25673345; cn 
25469 tn 9 sn 26)
```

The last line repeats with long delays, and after about an hour, the 
system eventually powers down.

# Troubleshooting Steps Taken

- Tested with different memory sticks to rule out media errors.
- Turned off the swap partition, but the issue persists.

# Observation

The error messages suggest an attempt to write to the filesystem after 
it should have been unmounted. The exact cause of this behavior is unclear.

# Request for Assistance

I am seeking insights or solutions to understand and resolve this issue, 
specifically:

- What might be causing the system to attempt writing to the USB stick 
during the final shutdown phase?

- Are there any known issues with USB boot devices on NetBSD 10.0 that 
could explain this behavior?

- Any suggestions for additional troubleshooting steps or configuration 
adjustments that could help mitigate this problem?

Thank you for your assistance.

Kind regards,
Matthias