Scrubs, SMART, & HDD Standby for home server

[par]

Surely this has been asked hundreds of times but I am looking for a conclusive list of what sort of tests/tweaks I should use for my new home server. Right now I am just at the defaults and am having trouble finding guidance.

Scrubs are defaulted to every 35 days, I assume this is sufficient.

SMART is not set by default, what is a proper schedule of long vs short tests?

HDD Standby/spindown is not set by default, what is something that makes sense for WD Red drives? I am not able to predict my usage apart from not using the system while sleeping. Not all too concerned about power consumption (which is already low) but rather getting the most life out of the drives.

Anything else I should consider?

 

[ewhac]

As a fellow n00b, don't take this as gospel, but:

Philosophy on scrubs: Scrubs will tell me about corrupted data/pools. I want to know about this as soon as possible. I don't have a feel for how much load a scrub puts on a system, so I don't know what's "too often." I have mine set to once every two weeks. I suspect once a week wouldn't be too frequent...

Philosophy on SMART: Based on the paper Google published a few years ago analyzing failure trends in their millions of hard drives, SMART turned out to have very little value in predicting drive failure. I automate SMART, but don't pay a lot of attention to it.

Philosophy on spin-down: I'm on considerably shakier ground here, as I haven't actually done the measurements. However, in my brief experience, the various daemons running in the system are going to access the drives a few times every hour, causing them to spin up. Thus, you won't see much energy savings unless your spindown timeout is aggressively brief. But frequent spinup/down cycles are widely regarded as increasing drive wear. My sense is that spindown is only an overall win if you have a lot of drives that you can keep spun down for hours at a time. If you have six or fewer drives, you'll save more energy replacing the incandescent bulbs in your house with CFLs/LEDs. I don't use spin-down.

 

[Dusan]

However, in my brief experience, the various daemons running in the system are going to access the drives a few times every hour, causing them to spin up.

No, FreeNAS daemons do not access the drives (unless you install jails). I have WD REDs set to spin down after 60 minutes of inactivity and it works reliably -- the disks stay in standby the entire night. With WD REDs there's one catch I described here: http://forums.freenas.org/threads/ata-idle-wd-red-drives.11773/#post-68854 (you can poll smart attributes even from an standby WD RED without waking it up, but polling the attributes while the drive is idle will reset the standby timer).

 

[par]

How can you tell when disks standby/spin up? Some way to monitor this when testing the Standby option? I have no idea if my jails will trigger the disk to spin up so I must monitor it myself to see.

 

[Dusan]

How can you tell when disks standby/spin up? Some way to monitor this when testing the Standby option?

I use this script: http://blog.raphaelabreu.com/2013/03/struggling-with-freenas-power-consumption-optmization/
You can find more options in this thread: http://forums.freenas.org/threads/how-to-find-out-if-a-drive-is-spinning-down-properly.2068/