[PavelVD]

Tell me, what command will unmount and park HDDs connected to USB? If you need to turn off the power. The router is located high on the cabinet and it is difficult to use the "USB-->USB Support-->Use SES Button to Remove Drives" button.
I tried poweroff, halt and shutdown - they didn't work.
Thank you.

[ho1Aetoo]

First of all, all programs that access the hard disk must be closed, otherwise it cannot be unmounted properly.

You can also try deactivating USB support in the menu.
Or you can use a robust file system.

[Alozaros]

use shutdown script to save your stop services and unmount commands it works ok….

[PavelVD]

Thanks! Does the "Use SET Button to Remove Drives" button execute any commands?

[lexridge]

While you can unmount the USB HDD from a script, you cannot "park" it from stock DDWRT. You would need Entware with something like hdparm installed, I believe. I do this on my Linux computer's backup drive which is a USB ext4 formatted drive. I mount via UUID to do a backup (automatically of course), it does the backup. Unmounts the drive, sets it to read only then spins it down. I wrote the script in this way in an attempt to prevent ransomware from possibly getting to my backup drive, if I were to ever contract one that is.

[ho1Aetoo]

It is not said that it works.
There is a USB SATA bridge in the enclosures and many of these controllers do not support the pass-through of ATA commands.

[mwchang]

[UnicornStallion]

I believe that most modern mechanical hard disks that have S.M.A.R.T. technology--which is basically all mechanical hard disks you might still be using--automatically park themselves when they lose power (using the kinetic energy stored in the platters and rotating spindle as it spins down.) Software parking an HDD is obsolete.