Do you guys spindown disks in zfs pools?

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james23

Active Member
Nov 18, 2014
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With only a few drives and only spinning down half day... I wouldn't as it's not worth the additional likelihood of failure, wearing out faster, etc...

Say you have 5 spun down for 10hrs a day... so they use 5*4w @ idle (estimate) = 20w * 10hrs = 200w saving per-day and * 30 = 6000 watts or 6kWh and then * that by your power cost per kW for me that is 25 cents now. $1.5/mo saving or $18/year. It would take 10+ years to 'pay' for a drive with the savings from power so ymmv with value of that vs. causing a failure... def. not worth it in MY opinion ;)
great break down on $! but others should certainly not forget cooling too! assuming you are aiming to maintain about the same ambient temperature (generally true) , you roughly should multiply those $ amounts by *2 (or *2.5-3 as no ac sys is 100% efficient). If you are putting out 200w of heat, your AC/HVAC has to remove 200w of heat (at < 100% efficiency)

so 5x drives and saving 3 - 5$ per mo (at 24 or 48 drives, it gets a bit more interesting $). Also worth noting, you can often change the "amount/level" of spin down too (however i can say for sure, that on a test server with 15 or 20x hgst drives, that middle spin down setting only saved me about 20w total, so 1-2w per drive less that it was normally idling at 7w).
Also worth noting, that when you fully spin down a drive, it is still using a small bit of power (i think .5 to 1w on my hgst , back when i tested some of this)

also HGST drives are popular due to their high reliability and low (used) costs, and many of those model often idle at 6-7w.

All that said, im not a big fan of doing any spin down settings, as i do feel it greatly increases drive failure rates.
 

eduncan911

The New James Dean
Jul 27, 2015
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eduncan911.com
I have to chime in here about long term usage of spinning down drives...

In short, my primary reason for spindown is heat. I've setup and ran many drive pools since 2007, where I designed the systems to use only 1 HDD at a time for watching a movie/streaming something. I designed the systems this way so that only 1 HDD spins up instead of an entire array to access a single file. I think that is the biggest architecture decision here to consider.

Note that now since I am upgrading everything to 10 Gbps at home, I am moving to ZFS and with that I'll keep all drives spinning in my next build (12x 10 TB drives, migrating 8 I previously had). This is because I don't want the wear and tear of all drives spinning up just to access a single file.

Heat can really build up in a closet or bedroom, much more than most know. I've had many builds, and like an earlier comment usually a drive gets full and gets replaced with much larger drives once it ages out - than a failure. Now with my new home, I've carefully handled heating and cooling loads in the server-room-under-the-stairs.

I've actually been keeping a log... Note: all drives were from various vendors, some Green, some Blue, some Baracuda, HGST, etc. Usually purchased in small batches of 3 to 4 at a time, to avoid bad-batch failures.

17x 1 TB drives: 2 failure - funny, the 2 failures were from 2 drives not marked for spin-down
22x 4 TB drives: 1 failure from an 7-year old disk, my oldest batch
8x 10 TB drives: 0 failures (still pretty new)

As for SSDs, I've had 8x SSD failures out of 15 since 2008 in laptops, desktops, and servers. And most where high-end consumer models. Now, two of those SSDs were my "cache" drives to write to my storage server first. So I killed them on purpose with TBs/mo of writing. But the other 6x SSD failures shows SSDs are just unreliable - I'd never trust my data on them.
 

ReturnedSword

Active Member
Jun 15, 2018
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Santa Monica, CA
Interestingly I've had the opposite experience with SSD vs HDD. I've had many HDD die on me, even the high-end consumer models, but never had an SSD die (mid-end to high-end consumer models). I have lower confidence with HDDs. Not that I trust any of my data to any type of medium. I try to make sure there are multiple copies.