I just buit my 4 x 1.5TB drives Freenas server. They are in RAID and I was wondering if I should set the disks to spin down after 1hr or 5 hrs or whatever...The point is I don't know if I should spin them down or not. What will give those disks the longer life??
You can save energy by letting the disks spin down. If they are 7200rpm disks they will use 6-9W when idling, or 0.5W when spinned down.
But spinning down and up alot will wear the drive and potentially lower lifetime. The best would be to let a drive running all the time with good cooling; good not meaning excessive. If you put a fan on one side of the HDD it may decrease lifetime as there is a huge temperature difference in the HDD metal internally, causing expansion/contraction that will tear a drive apart. The best lifetime with HDD would be in a vibration-less environment where it is running with a constant temperature on all sides of the HDD.
Green drives running at ~5400rpm do not need to be spinned down; they will idle at 3.5W which is quite low already.
Interesting. I may actually spin them down then. This is a home NAS that I will not be writing to or accessing more than once a day if that. I plan to maybe access the NAS twice a week... that may be sparse enough to consider a spin down???
But spinning down and up a lot will wear the drive and potentially lower lifetime.
This is not as big a problem as it once was. In the old days when you spun down a drive the heads would loose their air cushion and come to rest on the platter as it was slowing down - that caused wear and most drives were rated for something like 50,000 stop/start cycles because of it.
Most modern drives use loading ramps which let the heads be retracted beyond the edge of the disk so that there's no physical contact between them and the platters when the drive is spun down. As a result of this the drive specs that I've seen show ratings on the order of 300,000 stop/start cycles. That's a 10-year lifespan if the drives are stopped and started every 20 minutes during every hour of every day, 365 days a year.
That's nice to hear. However i also read stories about WD Green drives with head parking feature, which causes lower lifetime. Some opt to disable the feature, i just left it enabled. Have a full backup anyway so i'm not so worried about drive failure.
The lower rpm the better, honestly. The sequential speeds are more dependent on data density than on spindle speed, and random IOps... well thats what you got your SSD for the HDDs could be used to only handle large files thus sequential performance is the only relevant stat here.
It is the high rpm (7200, 10k, 15k) that might disppear the quickest, as they target the same market as small SSDs do; system disk and server storage. In both cases the HDD is inferior and the SSD vastly superior.
So i think WD Green drives are a logical choice to store large files or for backup purposes. More logical than a 7200rpm drive these days.
Why inferior? The current 1.5TB with 500GB-per-platter are the latest gen best HDDs you can buy. If you compare HDD versus SSD then yes HDDs are inferior; but of course we leave price out of the consideration here.
I would be happy with 4 x 1.5TB anyways; i think thats a great power efficient mass-storage setup.
So what I've decided to spin down my disks after 4 hours of inactivity for now. I was getting a serious heat problem as well because I was leaving them on. the disks in the middle of the 4 disk stack were around 56 degrees and would burn you to the touch. I just installed a fan infront of the disks and I will test by letting them spin for days to see if the fan makes THAT much of a difference. If the drives remain above 40 degrees then I may move the top disk to a 5.25 bay and stagger the bottom 3 disks. I think heat may be a bigger killer than multiple start ups so I think in the end I will enable spin down after inactivity, for good.