I am in desperate need of a bigger NAS and was wanting to go with this 24 slot case http://www.newegg.com/Product/Product.aspx?Item=N82E16811219038, but there are a few things I would like some opinions on. First I want such a large one so I have ample room for expansion as I am hoping to not need to replace anything for a long time. With that case I can just throw in some more drives in a new pool and not worry about it. Right now the biggest issue is power. I was looking at using this 3TB Seagate drive http://www.amazon.com/gp/product/B005T3GRLY/?tag=ozlp-20, but even at 1.2 that would still require ~29A 5V. They do sell a 20 slot case which I would consider, but I don't even know if that 1.2A is correct. Before I go too much further is it even a bad idea to do a 20 or 24 drive FreeNAS? If so why? Also anybody have any experience with trying to power that many drives? I know you can do stagger power on and I do plan on trying that, but I want to prepare for if that doesn't work. Also are those Seagate drives a good choice? I was planning on going WD because I have always had good experience with them, but I see many people saying avoid them for a NAS.
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Questions about large NAS
- Thread starter Onichan
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Honestly, I don't worry too much about the startup current. The important is to look at the operating watts and compare that to your power supply total watts. While it is possible to exceed the current rating of a voltage bus, any well established top tier power supply company will not give you abnormal current limits on the buses.
I have that exact case for 2 FreeNAS servers(one with 22 and one with 16 hard drives) and neither one peaks at 400watts during startup. I do not have staggered spinup on either machine(partly because the Seagate drives in one of them doesn't support staggered spinup). Both have 500watt power supplies, and both allow for startup current to exceed 125% of power supply continuous load for something like 30 seconds. I'd bet if you look at the manual for the power supply you have you'll find something about starting current has higher limits for a limited time also.
Be sure that model supports staggered spinup. Alot of Seagates don't if I remember correctly, and Seagate doesn't make the information on the staggered spinups easy to find(I couldn't find it easily when I just googled for it).
Choosing a hard drive model is hard to do. I have a mixture of a bunch of different models and brands. Personally, I've been using green WD drives and had good success. I used to use and swear by Seagates and wouldn't even look at other brands because I had such good results with Seagates compared to other brands, but it's hard to do now since everyone seems to just suck equally.
My home NAS uses 6 WD30EZRX(3TB) and 16 WD20EARS(2TB). If I had to build a new server today I'd stick with the WD30EZRX, but that's just my preference. I'd shy away from Seagates at this point based on prior experience with them having Serial ATA command issues with HALTing randomly. The drives I had would randomly stop working in an array, but would pass all diagnostics with no issues. This happened for about 1/2 the drives(they were bought at various times over a period of 3 months and had different firmware too!). Seagate won't help you because they say the hard drives are only meant for "desktop RAID" and anything except raid 0 and 1 in an Windows environment is "outside their recommended design".
I have that exact case for 2 FreeNAS servers(one with 22 and one with 16 hard drives) and neither one peaks at 400watts during startup. I do not have staggered spinup on either machine(partly because the Seagate drives in one of them doesn't support staggered spinup). Both have 500watt power supplies, and both allow for startup current to exceed 125% of power supply continuous load for something like 30 seconds. I'd bet if you look at the manual for the power supply you have you'll find something about starting current has higher limits for a limited time also.
Be sure that model supports staggered spinup. Alot of Seagates don't if I remember correctly, and Seagate doesn't make the information on the staggered spinups easy to find(I couldn't find it easily when I just googled for it).
Choosing a hard drive model is hard to do. I have a mixture of a bunch of different models and brands. Personally, I've been using green WD drives and had good success. I used to use and swear by Seagates and wouldn't even look at other brands because I had such good results with Seagates compared to other brands, but it's hard to do now since everyone seems to just suck equally.
My home NAS uses 6 WD30EZRX(3TB) and 16 WD20EARS(2TB). If I had to build a new server today I'd stick with the WD30EZRX, but that's just my preference. I'd shy away from Seagates at this point based on prior experience with them having Serial ATA command issues with HALTing randomly. The drives I had would randomly stop working in an array, but would pass all diagnostics with no issues. This happened for about 1/2 the drives(they were bought at various times over a period of 3 months and had different firmware too!). Seagate won't help you because they say the hard drives are only meant for "desktop RAID" and anything except raid 0 and 1 in an Windows environment is "outside their recommended design".
jgreco
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I had heard good power supplies do allow short over usage, I just wanted to try and avoid that as I am sure it would be better for the life of the PSU if you didn't do that. Also I have always been a WD fan as I have had issues with Seagate before, but I have heard the WD greens are bad for FreeNAS. If you are using them then I assume they are fine to use? Did you do anything special? I remember reading to do some update to them to prevent their spindown from happening so quickly or something like that. I'll have to search the forum some more to see if anybody has had issues with the WD greens and if not then I think I will use them, thanks.
Also I asked on the Seagate forum about startup power requirements and somebody responded with http://www.seagate.com/staticfiles/support/docs/manual/desktop/Barracuda 7200.14/100686584c.pdf and on page 17 it actually says the 5v isn't required for startup. So it seems like the other post I found on here is incorrect about that which is good news for me.
I thought that hard disks typically used 12v and nothing else. I wasn't going to try to debate someone else giving facts as each model could potentially be different.
Think about this though. How often do you really expect to power-on the server? Just about everyone in the forum talks about leaving the server on 24x7. Even on a reboot you aren't dealing with startup current.
Think about this though. How often do you really expect to power-on the server? Just about everyone in the forum talks about leaving the server on 24x7. Even on a reboot you aren't dealing with startup current.
That is true that it shouldn't be cold booted often, but I wanted to be safe. Though now it's not a problem.
jgreco
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noobsauce80: No, hard disks typically use 5VDC too.
Ohichan: I don't think I'd read that as "5V isn't required" for spinup. You always need to be powering the drive electronics. It looks to me like they've broken out spinup as a special item because of the engineering concerns for power supplies, and that the point they're making is that the only design consideration for extra power during spinup is the 12V.
Ohichan: I don't think I'd read that as "5V isn't required" for spinup. You always need to be powering the drive electronics. It looks to me like they've broken out spinup as a special item because of the engineering concerns for power supplies, and that the point they're making is that the only design consideration for extra power during spinup is the 12V.
Ah yeah I realize it's used for spinup. I meant to say there isn't any extra needed for spinup like there is for 12v.
Right. A motor will use several magnitudes more power than a hard drive controller. You could probably power 50+ hard drive controllers without issue on a typical 500w power supply.
Motors are absolutely terrible for power usage needs. I'm not just talking hard drive motors. I'm talking motors in general. The energy required to create the magnetic fields for motors to function is quite high.
There's a tradeoff between current and voltage. For a given power need, as voltage goes up the current can drop. Obviously, you don't want high current needs because that requires thick cables. So instead you design equipment to use the highest voltage available for high current needs. That's why hard disks, gaming video cards, etc use 12v instead of 5v. :)
For those interested, the math equation is Power = Current * Voltage.
Motors are absolutely terrible for power usage needs. I'm not just talking hard drive motors. I'm talking motors in general. The energy required to create the magnetic fields for motors to function is quite high.
There's a tradeoff between current and voltage. For a given power need, as voltage goes up the current can drop. Obviously, you don't want high current needs because that requires thick cables. So instead you design equipment to use the highest voltage available for high current needs. That's why hard disks, gaming video cards, etc use 12v instead of 5v. :)
For those interested, the math equation is Power = Current * Voltage.
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