What is the purpose of your NAS? Is it for media file ?
What is your system spec? 100 watt idle is very high? Do you use the machine to host VM as well ?
Do you want to spin down drives to save power?
Mainly as an SMB file server to backup the other computers in the home, which have lots of storage. Media server also possibly, with clients that support WoL like Jriver MC, or manual wake up through WOL app. The wakeup part is already working - it's the "go back to sleep automatically when not in use" part which is not.
I don't use VMs. Spinning down the five 10TB SATA WD100EMAZ drives would only bring idle power down by 15W. I have already experimented with spinning them down and measured that with a kill-a-watt.
This is a fairly powerful computer, with all 7 slots on the motherboard filled, and which can handle a large number of SATA or SAS drives, and I don't think there is any way to reduce the power usage significantly without making it a much less powerful one. Even if I could bring down the total idle wattage to, say, 50W, I would still want the power saving feature to put it to sleep when not in use. I think it would be comfortable running it 24/7 if it was 10-15W total. The case fans alone take about that much according to my Kill-a-watt.
I designed the computer to be very powerful on purpose. I never intended it to run 24x7 . I assumed there was a way under Linux to do power management, as I have been doing that very simply under Windows for years. Is this not the case ? The main reason I switched the box to Linux was lack of ZFS on Win10, and not wanting to pay big $$$ for Windows server and whatever software storage solution MS has these days for a home NAS. I see that there is actually a ZFS port of it to Windows, but I don't know if it's really reliable enough to run it or not.
I will post the full hardware specs below, but please understand that I'm not looking to make any hardware changes here, only software changes. Responses telling me to remove sticks of RAM, shrink the PSU, or removing PCIe controllers, won't be helpful. There is a very good reason for every single piece of hardware in that machine, and it needs to stay. I don't want the thread to get derailed on hardware issues.
With that said, the full hardware specs are as follows :
Cooler Master HAF-XM case with 5 case fans : 3 x 200m fans, 1 x 230mm fan, 1 x 140mm fan. All are 3-pin, except one of the 200mm which was just replaced with a Noctua 4-pin model.
Raidmax RX-1200AE PSU
Asus Z170-AR motherboard
i5-6600k CPU
Noctua NH-D14 cooler (dual fan cooler, both 3 pins)
2x16GB DDR4-3000 RAM (running at 2400 speed)
1 x Aquantia AQN-107 10 Gbps ethernet NIC, PCIe x4
1 x LSI 9207-8i SAS controller, PCIe 3.0 x8
1 x LSI 9207-4i4e SAS controller, PCIe 3.0 x8
3 x Silicon Image 3132 eSATA controllers, PCIe 1.0 x 1 (for 3 x SANS external 4-port eSATA port multiplier enclosures, not supported on LSI controller, or Intel controller)
1 x Adaptec 29320 PCI SCSI controller (for an old external HP DDS-4 tape drive)
5 x WD100EMAZ 10TB SATA drives
1 x Kingston 96GB SSD (OS boot drive)
Drive docks with plenty of remaining drive bays in the main case for backup drives. 3 x 3.5 hotswap in the front, 5 x 2.5 hotswap in the front. Also have space remaining for one more 1 x 3.5 internally . All bays are hooked up to either the LSI SAS or Intel SATA controller.
USB 3.0 4-port front hub, with card reader, in a 5.25 bay. Could be removed to add space for 2 more SATA drives (1 x 3.5, 1 x 2.5 ) if needed.
As I said, it's a fairly beefy machine that I don't want to run 24 x 7, but only when needed.