Energy management

Discussion about hard drive spin down (standby) feature of NAS.
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pbleras
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Energy management

Post by pbleras » Sun Mar 04, 2018 9:08 pm

Hello everybody.
Im going to buy a qnap, but I have some questions about sleep mode. How does it work? If the nas is sleeping, and Im going to use my PC, in order to open some files in the nas, does it wake up automatically?
Thanks for your help...

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Briain
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Re: Energy management

Post by Briain » Mon Mar 05, 2018 12:16 am

Hi

A very warm welcome to the Qnap community forum! :)

Yes; there are actually two states of 'sleep mode' that can be configured:

There is a deep sleep mode (sort of like Windows hibernation mode) whereby almost all of the NAS is switched off other than its Ethernet interface, so that means that as well as resuming it via its power button, it can also be remotely woken by sending it a so-called magic packet (WoL or 'wake on LAN' packet). From a Linux machine, this is simply a command you type in via your terminal, or from a phone/tablet, there are WoL applets you can use (I use one from an iPad to wake a Windows machine that sits in my cupboard).

A far less deep sleep mode (and this is the one you want) is to keep more of the electronics alive, but just set the disks to spin down after x minutes of inactivity (which is very simple to set up via the Qnap's web interface; see screen-shot below). In my case, as you can see it is disabled, but you can see the tick box where I could enable it, and the box in which you select how many minutes (after the last access) after which it will spin the disk(s) down:

Screenshot from 2018-03-04 15-57-43.png

(click on the above to see the full sized image)

This means it uses minimal power, but when you access it to retrieve a file (e.g access the NAS share from your PC) it then automatically spins the disks up and thus the file is available in a few seconds (these disks spin up pretty swiftly).

------You can stop reading now (which would probably be very wise) but, just in case you are interested------

There is also a third 'sleep option' (and it is my preferred one):

So yes, the second one is what you asked for, but just in case you are interested, it might not actually be the optimal solution in every case. On paper, the disk spin-down sounds like the golden solution, but it is worth remembering that with careful choice of disks, they might not take much additional power when spinning. For example, one of my Qnap NAS units (a TS-453) has two WD Red (each 3 TB) set up in a RAID 1 array. Unlike power greedy server grade disks, these are 'NAS grade' disks, and are not only optimised for a NAS environment (for reasons outside the scope of this post) but they are also designed to be very power efficient, and the difference between them spinning and being spun down is only about 3 Watts each. So for two, leaving them spinning all the time equates to only an additional 6 W of power being drawn.

So why would you consider unnecessarily 'wasting' these 6 Watts? Well, firstly, disks like to be kept at a constant temperature, but when you spin them up, their temperature will change from ambient (say, 20 deg) to about 30 deg, then after they spin down, they will then cool back down to 20 deg. If you leave disks spinning, they can last for many years longer than you'd expect them to last (I have seen some media servers - Linn Kivor music servers - with multiple disks that have been spinning since 2004, and most are still working; the bearings in the customers' electricity meters must be well worn down by now, though) but being electromechanical devices, I think that frequent temperature cycling can result in them dying a lot sooner.

Okay, if you access it twice a day, that's only a few temperature cycles, but what you find - in the real world - is that whenever you fire up a PC on your network, it could spin the disks up. Also, they spin up at 3 AM for Qnap 'house-keeping' activities. Also, if using it as a media server, media devices can spin them up. When I looked at my own NAS, I discovered that they were being spun up and down between 6 and 10 times per day (which is a lot of temperature cycling) so I elected to leave them spinning 24/7.

It is worth now considering what that 6 Watts means in terms of annual spend. Assuming that you had one NAS with a pair of WD Red disks (like my TS-453A) and somehow got it to leave the disks spun down for an entire year (which means never using it) it would only take 6 Watts less than the same NAS with these disks left spinning 24/7, and if you do the sums, that equates to the same price of a single pint of beer in a city centre bar, so for the price of 1 pint of beer per year, you can have your disks sitting at a constant temperature (and if they last longer than ones being temperature cycled, then you will be saving money - a lot more than a pint per year - by not having to replace them so often) so for these reasons, I have my NAS set to keep them spinning.

Sorry, not as short as answer as you perhaps hoped for, but it is interesting to consider the overall picture when deciding whether to use use disk hibernation, or not (and thus also which disks to chose). If you have an 6 bay NAS with 6 server grade disks (each taking 10 Watts to spin) then that is a very different story, but for a small modern NAS unit with WD Red disks, I would recommend leaving them spinning as it will likely actually save you money in the longer term! It's worth noting that I do have a 6 bay NAS with 6 enterprise grade disks in it, but I specifically updated to a newer model due to them being more power efficient, and specifically so that I could use fewer (and larger) WD Red disks due to my desire to keep them spinning 24/7 (I now only power that big NAS up when using it to back up my TS-453).

I can almost hear you snoring, from here!!! :lol:

Bri :D
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TS-119, 1 X Seagate ~~ TS-219, 2 X Seagate (R1) ~~ TS-453A, 2 X 3 TB WD Red (R1) ~~ TS-659, 5 X 1 TB Hitachi Enterprise (R6)
APC Smart-UPS 750

pbleras
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Re: Energy management

Post by pbleras » Mon Mar 05, 2018 10:42 pm

Thank you very much for yor answer. Its very helpful.
Regards.

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storageman
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Re: Energy management

Post by storageman » Mon Mar 05, 2018 11:03 pm

Actually disk standby is hard to achieve due to so many background processes.

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Briain
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Re: Energy management

Post by Briain » Mon Mar 05, 2018 11:57 pm

storageman wrote:Actually disk standby is hard to achieve due to so many background processes.

It was quite practical a few years ago (though I had a quiet network and didn't have many additional applications running on the Qnap; remember, I am a bit of a Luddite ;) ) but I have no idea how 'achievable' it is in current builds (what with all these new features we now have). What I found was that when I used to run a Windows PC (I now use Debian) whenever it was booted up, it triggered a disk spin up on the Qnap and it was something that I was always concious of. It also needed a mild amount of managing (weekly checking of SMART start-stop-count to ensure things weren't going nuts). As I noted above, I specifically purchased a TS-453 Pro (and chose the WD Red disks) to give me a system which consumes very little energy with the disks spinning (far less than the TS-659 consumes with the disks spun down, in fact) and it is really nice to no longer have to bother about it.

Bri :)

Incidentally, I had a cool system running whereby the disks were automatically set to enable spin down (set in the disk firmware) some time after the 3 AM housekeeping jobs (triggered by crontab) then not long after, they were set to continuous spin mode (doing so did not spin them up). So that meant it would spin them down until next accessed (i.e. by accessing data on a share) then once spun up, they would remain spinning until after the following day's 3 AM tasks. It all worked well and if no access was required, they did stay spun down until the next day's housekeeping tasks. I ran it like that for a few months, then it crossed my mind that every day I was triggering a couple of writes to the flash in all the disk controller boards. I thought of doing some research (seeing what was on the controller boards) to work out whether they could handle that sort of punishment, but I ended up just buying a more modern Qnap. Actually, I do recall writing a long - probably very long - forum post about it all, back in the day! ;)
TS-119, 1 X Seagate ~~ TS-219, 2 X Seagate (R1) ~~ TS-453A, 2 X 3 TB WD Red (R1) ~~ TS-659, 5 X 1 TB Hitachi Enterprise (R6)
APC Smart-UPS 750

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