# Powering down disks for RAID-Z



## Pushrod (Oct 2, 2011)

I have a 4-disk RAID-Z that does not get accessed for about 4 hours per day. I'd like to power down the disks during this time, just to save the planet and my wallet that small amount. Is there a good, reliable way to do this?


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## toddnni (Oct 3, 2011)

I don't see any problems with it. I spin down my ZFS mirror daily and the drives spin up when they are accessed.

I use *atacontrol spindown*, but have I also tried *camcontrol idle* when using 
	
	



```
ahci_load="YES"
```


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## gossamer (Oct 4, 2011)

@toddnni: I havent tried it yet, but basically i could use:


```
atacontrol spindown ad10 900 &
atacontrol spindown ad12 900 &
atacontrol spindown ad14 900 &
atacontrol spindown ad16 900 &
```

and that should spindown whole raidz pool after 900s if there is no request access on either of disks ?

i have also read somewhere that i need to turn of S.M.A.R.T. option in BIOS to be able to use spindown (at least without unexpected behavior). Any comments on that ?


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## toddnni (Oct 4, 2011)

gossamer,

ampersands (&) aren't needed with atacontrol and I would suggest longer timeout.

I haven't yet seen a motherboard with SMART capabilities, but smartd.conf(5) suggests that SMART checks may cause drives to spin up. There is an option -n to prevent checks when drives are in lower power state.


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## Pushrod (Oct 26, 2011)

I looked into this a bit more, and found that with worst-case figures, shutting down my disks for 4 hours per day would save me roughly 5kWh per year, which is 40 cents.

I decided to keep them running. Spinning them down often increases the chances of them failing. Not worth 40c/year.


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