I've just rebooted it, and selected Spin Down on the Main section and this is what it showed:
Jan 18 16:16:19 Tower emhttpd: req (2): cmdSpindownAll=true&startState=STARTED&csrf_token=****************
Jan 18 16:16:19 Tower emhttpd: Spinning down all drives...
Jan 18 16:16:19 Tower kernel: mdcmd (48): spindown 0
Jan 18 16:16:19 Tower kernel: mdcmd (49): spindown 1
Jan 18 16:16:19 Tower kernel: mdcmd (50): spindown 2
Jan 18 16:16:19 Tower kernel: mdcmd (51): spindown 3
Jan 18 16:16:19 Tower kernel: mdcmd (52): spindown 4
Jan 18 16:16:19 Tower kernel: mdcmd (53): spindown 5
Jan 18 16:16:19 Tower kernel: mdcmd (54): spindown 6
Jan 18 16:16:19 Tower kernel: mdcmd (55): spindown 7
Jan 18 16:16:19 Tower kernel: mdcmd (56): spindown 8
Jan 18 16:16:19 Tower kernel: mdcmd (57): spindown 9
Jan 18 16:16:19 Tower kernel: mdcmd (58): spindown 10
Jan 18 16:16:19 Tower emhttpd: shcmd (150): /usr/sbin/hdparm -y /dev/nvme0n1
Jan 18 16:16:19 Tower kernel: mdcmd (59): spindown 11
Jan 18 16:16:19 Tower root: HDIO_DRIVE_CMD(standby) failed: Inappropriate ioctl for device
Jan 18 16:16:19 Tower root:
Jan 18 16:16:19 Tower root: /dev/nvme0n1:
Jan 18 16:16:19 Tower root: issuing standby command
Jan 18 16:16:19 Tower emhttpd: shcmd (150): exit status: 25
Jan 18 16:16:19 Tower emhttpd: shcmd (151): /usr/sbin/hdparm -y /dev/nvme1n1
Jan 18 16:16:19 Tower root: HDIO_DRIVE_CMD(standby) failed: Inappropriate ioctl for device
Jan 18 16:16:19 Tower root:
Jan 18 16:16:19 Tower root: /dev/nvme1n1:
Jan 18 16:16:19 Tower root: issuing standby command
Jan 18 16:16:19 Tower emhttpd: shcmd (151): exit status: 25
Jan 18 16:16:19 Tower rsyslogd: Child 7692 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:16:19 Tower rsyslogd: Child 7726 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:16:19 Tower rsyslogd: Child 7760 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:16:19 Tower rsyslogd: Child 7828 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:16:19 Tower rsyslogd: Child 7845 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:16:19 Tower rsyslogd: Child 7862 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
(Highlighted in yellow are the two NVME drives I installed today)
After entering the code you mentioned above and doing it again, this is what it shows:
Jan 18 16:20:14 Tower emhttpd: req (4): cmdSpindownAll=true&startState=STARTED&csrf_token=****************
Jan 18 16:20:14 Tower emhttpd: Spinning down all drives...
Jan 18 16:20:14 Tower kernel: mdcmd (72): spindown 0
Jan 18 16:20:14 Tower kernel: mdcmd (73): spindown 1
Jan 18 16:20:14 Tower kernel: mdcmd (74): spindown 2
Jan 18 16:20:14 Tower kernel: mdcmd (75): spindown 3
Jan 18 16:20:14 Tower kernel: mdcmd (76): spindown 4
Jan 18 16:20:14 Tower kernel: mdcmd (77): spindown 5
Jan 18 16:20:14 Tower kernel: mdcmd (78): spindown 6
Jan 18 16:20:14 Tower kernel: mdcmd (79): spindown 7
Jan 18 16:20:14 Tower kernel: mdcmd (80): spindown 8
Jan 18 16:20:14 Tower kernel: mdcmd (81): spindown 9
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower kernel: mdcmd (82): spindown 10
Jan 18 16:20:14 Tower kernel: mdcmd (83): spindown 11
Jan 18 16:20:14 Tower emhttpd: shcmd (162): /usr/sbin/hdparm -y /dev/nvme0n1
Jan 18 16:20:14 Tower root: HDIO_DRIVE_CMD(standby) failed: Inappropriate ioctl for device
Jan 18 16:20:14 Tower root:
Jan 18 16:20:14 Tower root: /dev/nvme0n1:
Jan 18 16:20:14 Tower root: issuing standby command
Jan 18 16:20:14 Tower emhttpd: shcmd (162): exit status: 25
Jan 18 16:20:14 Tower emhttpd: shcmd (163): /usr/sbin/hdparm -y /dev/nvme1n1
Jan 18 16:20:14 Tower root: HDIO_DRIVE_CMD(standby) failed: Inappropriate ioctl for device
Jan 18 16:20:14 Tower root:
Jan 18 16:20:14 Tower root: /dev/nvme1n1:
Jan 18 16:20:14 Tower root: issuing standby command
Jan 18 16:20:14 Tower emhttpd: shcmd (163): exit status: 25
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdb S=0
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdf S=1
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdg S=2
Jan 18 16:20:14 Tower rsyslogd: Child 8893 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdd S=3
Jan 18 16:20:14 Tower rsyslogd: Child 8912 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdl S=4
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdk S=5
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdh S=6
Jan 18 16:20:14 Tower rsyslogd: Child 8969 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdm S=7
Jan 18 16:20:14 Tower rsyslogd: Child 8988 has terminated, reaped by main-loop. [v8.33.1 try http://www.rsyslog.com/e/0 ]
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdi S=8
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdj S=9
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sdc S=10
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter triggered
Jan 18 16:20:14 Tower SAS Assist v0.83: debug: syslog filter, R=sde S=11
(Highlighted in yellow are the two NVME drives I installed today)