Pondering over harddrives (2.5 / 3.5, power consumption)

[rind]

Hi all,

I am about to put together my first proper NAS after using old old hardware laying around and hiding the result in my basement :)
Have done a bit of reading in the forums by now and found lots of helpful stuff.. still for days I am pondering about what to order...

I am kind of on a budget and basically want the system to be as power efficient as can be.

The base will be the ASUS E35M1-I (no need for HDMI, usb3 and co) and 8g RAM.
Now here is my question: why does everybody only ever use 3.5" HDDs? are the 2.5" considerably worse in terms of speed / reliability / power ?
When I look at the lists at Tom's hardware guide, 2.5" idle power consumption (obviously) is much less but also the "performance per watt" ratings are much better
2.5": http://www.tomshardware.com/charts/2012-mobile-hdd-charts/-23-Performance-per-Watt,3006.html
3.5": http://www.tomshardware.com/charts/...rformance-per-Watt-Streaming-Writes,2921.html

maybe I am horribly overlooking something? :)

the whole thing came up to me because I looked at a lot of cases and it seems to me you can find many more better priced cases that are actually made for 2.5" (not that I would buy the drives according to a case, but thats how I came to think about it)

One more thing. If I want to more or less max out my gbit lan, doe's it matter whether sataII or sataIII drives/ports are used?
I am happy if I can get a decent read/write rate over CIFS and FTP like most of the guys in this
thread http://forums.freenas.org/showthread.php?27-AMD-E-350-Thread-(now-in-new-forum-)
can I achieve that with 2.5" drives or do they have a flaw I don't see?
because if no, it seems I can lower the power consumption of the good thing quite a bit compared to using the standard hdd's

thanks for every reply
rindl

 

[Joshua Parker Ruehlig]

I believe because 2.5inch harddrives have smaller spindles they are more likely to get damaged and wear out. I know having larger platter (harddrives with 3 larger platter compared to 4 smaller ones) makes a harddrive more reliable.
T
I doubt sata2 vs 3 will affect anything over gigabit lan. sata 2 is already 3 gigabit. You may also want to look at pci bandwith to your sata ports. Though if you are using the onboard sata controller you can't change anything about it.

 

[paleoN]

Now here is my question: why does everybody only ever use 3.5" HDDs? are the 2.5" considerably worse in terms of speed / reliability / power ?

Mainly because they are larger & cheaper?

One more thing. If I want to more or less max out my gbit lan, doe's it matter whether sataII or sataIII drives/ports are used?
I am happy if I can get a decent read/write rate over CIFS and FTP like most of the guys in this
thread http://forums.freenas.org/showthread.php?27-AMD-E-350-Thread-(now-in-new-forum-)
can I achieve that with 2.5" drives or do they have a flaw I don't see?
because if no, it seems I can lower the power consumption of the good thing quite a bit compared to using the standard hdd's

The highest performing spinning enterprise SAS drives are 2.5". It doesn't matter which sata ports you use. Either will easily max gigabit. IMO, the power consumption isn't that big unless you were using 10K rpm VelociRaptor.

 

[rind]

thank you for your replies

IMO, the power consumption isn't that big unless you were using 10K rpm VelociRaptor.

The idle consumption of lets say Seagate Barracuda is 3.6W, of e.g. the WD Scorpio Blue WD10JPVT 0.6W. assuming the system is in idle most of the day, you don't think this will make a difference?
price difference is 10-20€ and I am only going to get 1TB drives anyway.


if 3.5" fits more platters than 2.5" and I compare two drives with 1TB, wouldn't I have 1TB spread over less platters in 2.5"? Less Platters = less failure potential? I don't know about the smaler spindles.

 

[paleoN]

The idle consumption of lets say Seagate Barracuda is 3.6W, of e.g. the WD Scorpio Blue WD10JPVT 0.6W. assuming the system is in idle most of the day, you don't think this will make a difference?
price difference is 10-20€ and I am only going to get 1TB drives anyway.

Not much. Especially if you spin the drives down. I probably should have started with a disclaimer that I'm not overly concerned about power. If they have it in the size you want and price is negligible go for it. Just don't have the drive park its heads every 5 minutes.

if 3.5" fits more platters than 2.5" and I compare two drives with 1TB, wouldn't I have 1TB spread over less platters in 2.5"? Less Platters = less failure potential? I don't know about the smaler spindles.

Actually a 3.5" would likely have less platters as the platters can be larger. Are there any single platter 2.5" drives? There very well could be. I know there are for 3.5".

Less platters also means greater density. Which means increased error rate. In fact there was an enterprise drive, forget which one, for version 2 where they increased the number of platters by 1 to decrease the density per platter.

What's your planned zpool configuration anyway?

 

[rind]

hmm, ok, if less platters means greater density and 3.5" likely has less as you say, thats another argument for 2.5".
I don't know, I am probably overthinking this, as I said, I just checked out the "performance per watt" tabels and thought that at that rate 2.5" would be much more worth it.

Anyway, not having the drives spin down every 5 minutes is a good advice for 2.5" and 3.5" alike, I guess

Right now I am only thinking of 3*1TB (raid-z), maybe adding more later.

p.s. are those cave paintings from africa in your avatar? just came from there, loved it.

 

[cyberjock]

You are overthinking it a bit.

There's many factors that play a part in picking the "best" hard drive.

Manufacturer and model matter because you WANT as few platters as possible, but you also WANT data to have the most space per bit. It's a double edged sword. Unless you sit down and do the math based on platter areal density and compare it to other drives it's hard to determine which is "better".

Of course, if "Brand A" fails more often than "Brand B" then you might find that "Brand B" is the absolute worst in number of platters and/or density.

Then you can talk about the power supply efficiency. It is possible to buy a bunch of lower powered hard drives and have them draw more power than a bunch of higher powered hard drives with the exact same power supply! Power supplies do not have uniform efficiency between 0 and 100% load. If you use 15w 24x7 for a year(roughly comparing 3x3.5 to 3x2.5" drives) you are talking only about $16.00 a year!

Overall, it's a gamble when you buy a bunch of drives. Just make the purchase keeping in mind what models/brands have worked for you in the past and what drives will work as you intend to use them.

Unless you have inside information as to actual "real world" lifespans of these drives there's no way you're going to "guess" the absolute best. As long as you pick what you feel you can handle it doesn't matter.

So what's my opinion? Quit overthinking it and go buy the drives that will make you happy and quit worrying about the menutia. You have MUCH bigger dragons to slay than worrying about $15. If you buy a model that's unreliable but more power efficient your RMA shipping costs will exceed the money you'll save in a year. If you are really going to argue with yourself over $15 worth of electricity in a year you shouldn't be in this business. ;)

 

[jgreco]

I'm going to argue the opposite point... it makes *sense* to worry about the watts, but it is clearly just one dimension of a complex problem. Heat is one of the killers of hard drives. A 7200RPM disk is usually faster than a 5400RPM disk, but it also runs hotter, and is somewhat more prone to failure.

A Hitachi 7K3000 is around 6 watts idle, 12 watts busy, a 5K3000 is around 4 watts idle. Hitachi claims the 5K unit is about 29% more power-efficient. Don't need speed? Get the 5400. Save a bit. But if you don't *need* a 3TB HDD...?

For example, I've got some WD7500AAKS (750GB) in one of our FreeNAS boxes right now. They perform pretty well, but running four at about 10 watts apiece, they really drive the power consumption of a N36L up. You can get the Seagate Momentus XT, in a 2.5" form factor, a drive that takes less than a watt and a half... four of them run five watts. Saving 35 watts 24x7 for five years at 14c/kWh saves hundreds of dollars, PLUS you get adaptive hybrid acceleration, PLUS you get less heat ... I know a lot of FreeNAS users don't need to worry about cooling, in a home use environment, but if you heat your server room, it costs money to cool it too. If you use an easy rule of thumb that it costs about as much to cool as it did to burn the power, the $215 in electric saved becomes more like $430 ... which comes darn close to paying for the 2.5" drives outright.

 

[rind]

@noobsauce80
the problem seems to be the same with whatever hardware you buy, since I am no insider, I can only rely on reviews, tests, tabels, figures.

mind you that the average electricity bill is higher in Europe (where I am) than in the us. (taken jgrecos rate of 14c/kWh --> e.g. Germany is at 38c/kWh)
besides.. at this point, its not all about money for me.. rather my.. lets say feeling with that cube filled with electric parts (the NAS) I will constantly be feeding with energy ;)

well, I have got another month or so before I can buy the hardware and go forth to slay dragons :)
right now I am thinking about those drives

2.5" WD Scorpio Blue WD10JPVT 96€ (1TB 5400rpm sata3g/s 8MB)
2.5" Samsung M8 94€ (1TB 5400rpm sata3g/s 8MB)
3.5" WD Caviar Green 87€ (1TB 5400rpm sata6g/s 64MB)
3.5" Seagate Baracuda 85€ (1TB 7200rpm sata3g/s 32MB)

so maximum price diff would be about 10€ while the 2.5" having a sixth of the power consumption.
all the 2.5" over 500gb have two platters and a high density

@jgreco
the momentus XT seems great (PC7 benchmarks) but those really are a stepp to expensive :(
but you point is exactly what makes me think about all this.
well, I have got another month or so before I can buy the hardware and go forth to slay dragons ;)

 

[jgreco]

As I said, it's just one dimension of a complex problem. When we built some new ESXi hosts here last year, I went out of my way to purchase one of the most efficient power supplies I could locate, even though that tacked $50-$75 on to the cost. The cost recovery period on saving the extra ~3-5 watts over a lower-efficiency but still 80PLUS certified power supply is pretty much longer than the expected service life of the gear, but I can look at the things and feel good about it.

But that's kind of the point noobsauce80 made: "go buy the drives that will make you happy" was right, but it seems that finding this stuff out and then making an informed decision amongst several imperfect options is what you need to do to get you that happy solution.

Two more factors to mention:

1) A laptop hard drive is often made to be a little more resilient than a 3.5" hard drive, as they're meant for laptops and for some motion during use.

2) That's often offset by most laptop hard drives not being rated for a 100% duty cycle (i.e. use in a server 24/7).

http://www.seagate.com/staticfiles/support/samsung/docs/M8 Product Data Sheet_rev1.1.pdf

Samsung/Seagate helpfully don't identify the duty cycle for the M8. Oh and that figures, WD doesn't either.

http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701278.pdf

I'd suggest being careful and see if you can make sure your drives spin down when idle for long periods. Safer.

 

[paleoN]

But that's kind of the point noobsauce80 made: "go buy the drives that will make you happy" was right, but it seems that finding this stuff out and then making an informed decision amongst several imperfect options is what you need to do to get you that happy solution.

The two points I was attempting to make, which jgreco & noobsauce80 did, were:

1. It's a trade off no matter what way you go
2. Price difference is neglible so buy the drives, 2.5", you wanted

You would be one of a few people using 2.5" drives. Which would be another reason to do it at least for me.

Right now I am only thinking of 3*1TB (raid-z), maybe adding more later.

I would suggest ordering 4 drives and keep the extra as a cold spare.

p.s. are those cave paintings from africa in your avatar? just came from there, loved it.

From the Paleolithic era at Lascaux cave in France.

 

[mav@]

Just a note, that if your system will not need hot-plug and power consumption is critical, You may save about 0.7W per SATA device by enabling SATA interface power management. For AHCI-compatible controller you may to it by adding few lines like hint.ahcich.X.pm_level=5 to loader.conf.

 

[rind]

You would be one of a few people using 2.5" drives. Which would be another reason to do it at least for me.

Hehe, that encourages me :)

thank you for the hint mav@ !


I can't believe it.. as soon as I was just going to make up my mind.. the WD caviar red is released..
http://www.storagereview.com/western_digital_red_nas_hard_drive_review_wd30efrx

 

[jgreco]

I can't believe it.. as soon as I was just going to make up my mind.. the WD caviar red is released..
http://www.storagereview.com/western_digital_red_nas_hard_drive_review_wd30efrx

Oh, awesome. I've been wondering when someone was going to do something like that.