Building my first FreeNAS system, build advice

[Chris Moore]

I have been pondering about this for some time. What would be the benefit of running 1 vs 2 power supplies?
I would guess that noise might be a factor here, but does this also give a power consumption benefit?

There is a slight reduction in power use, but it is not much. Last time I tried it, the difference was around 20 watts and for the small savings, I would rather have the redundancy. I recognize that I am probably in the minority, but my primary home NAS has triple redundancy on the power and my backup NAS has dual redundant supplies. I just want it to work. Especially when I have a day like today, I don't want to be fighting a hardware problem when I get home.

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[Inxsible]

I have been pondering about this for some time. What would be the benefit of running 1 vs 2 power supplies?

That would depend an the mode the PSUs are running.

• Balanced - usually means both PSU handle 50/50.
  
• Efficiency or Switched-- usually means 1 runs, the other is idle or in stand-by until the 1st one goes down.

Different manufacturers have different modes or mode names -- some with greater granularity. When a PSU is on stand-by, it still draws power but it's quite less. Say 20-25W for a decently rated (80Plus Gold/Platinum) PSU. Not too sure about the Bronze ones.

I would guess that noise might be a factor here, but does this also give a power consumption benefit?

Noise is a factor, but running only 1 depends on the mode the PSUs are being run as.

 

[Inxsible]

Also, you cannot change the PSUs in a chassis willy-nilly. The PDB might not accept the plug from a different PSU. See this post.

Best bet would be to change to a lower PSU in the same range of chassis -- check the manual and see what other PSU wattage/model # are available for your chassis. Better yet, confirm it with Supermicro support whether a particular PSU would work with your chassis.

 

[rvassar]

I have been pondering about this for some time. What would be the benefit of running 1 vs 2 power supplies?
I would guess that noise might be a factor here, but does this also give a power consumption benefit?

@Kiskaa, you stated that you did this due to the fact that this was not a mission-critical server. Did you have other reasons to remove one?

Server grade hardware generally gets ratings for mean time to failure (MTBF), serviceability, and a concept of uptime sometimes expressed as a percentage. Though the latter is often by contractual agreement and perhaps not published.

Given that there are roughly 31,536,000 seconds in a year (dependant on leap year, leap seconds, etc...):

99% or "Two Nines" gets you 3.65 days of down time per year.
99.9% or "three nines" gets you 0.365 days (8.7 hours) of down time.
99.99% or "four nines" gets you 52.5 minutes of down time.
And the Telco holy grail five nines / 99.999% up time, 315 seconds, or 5.2 minutes down time per year.

Meeting a two nines requirement is pretty easy. Most any modern PC will fit the bill. Add same day parts service & ECC and it could be three nines. But getting four nines requires you to begin addressing MTBF & serviceability issues, a power supply is a single point of failure, both from the PSU's internal standpoint, but also from the grid connection standpoint. Similar issue with fans, disks, etc... Hot swap disk become important somewhere around three nines, depending on the count. Somewhere approaching four nines you start seeing hot swappable PSU's, that can be replaced with zero down time. The only five nines systems I've worked on were essentially fully redundant, with a spare host in a failover configuration, and they came with million dollar service contracts.

But... I can only guess the specifics of his case. As many of us here have observed, twice the parts, twice the things to fail. So if he doesn't have four nines grid power, and the load is handled by a single PSU, he doesn't need to keep the second power supply running. He's may be better off keeping it on a shelf somewhere as a tested cold spare. The single PSU may prove more efficient operating at a higher load point as well.

Rob

 

[Chris Moore]

Rob

Rob shared some good information there and it illustrates (very nicely) one of the reasons I like to keep my redundant power supplies installed. I have had a power supply fail in one of my (years ago) previous NAS builds that did not have redundant hot-swap supplies. It took my NAS down for days because I had to order another supply and wait for it to come in the mail.
Since I switched to using systems with redundant supplies, I have had another power supply fail, but it just caused an alarm from the chassis that I was able to silence (thankfully) but no down time. I ordered a replacement power supply and installed it when it arrived and the server was never offline for even a moment. I like that because my data was never at risk and my family was never inconvenienced except that they had to listen to the beeping from the server until I got home and silenced the alarm.
If you are willing to risk your data by having your server go down for a failed power supply, go for it. You might save a couple dollars on electricity, but I doubt that it will save you enough on your power bill to be significant compared to the personal value you must place on your data to have invested in a server to begin with.

 

[Kiskaa]

I did some research on the redundant power supply power usage. I read an article that was linked in @Chris Moore footer documents. In there it explained about the power difference. Removing one of the PSU`s doesn't actually half the power being used, its around 10%. Since I have 2 and replace one if one fails, I have another to put right in, and reducing the power reduction needed (again I stress this isn't a mission-critical server, it's being used at home, and anything important will have cloud sync backups) Also, whatever (if) I replace the unit, I`ll be buying 2, so I have one spare.
The 720watt I was talking about is compatible with my server, as it's an official PSU for my chassis, however, I was sure it was Platinum rated, once I get home I`ll check again.

To those asking why I did remove one, it was purely to save a little power being used to be a bit more "green" (since it`ll be on 24/7) and generate marginally less heat, and I guess noise too. There was no other reason for this than the above.

 

[Chris Moore]

it was purely to save a little power being used to be a bit more "green"

How much do you save? Is it really worth the risk? I know that you have backups, but it takes time to restore from backup.

 

[Kiskaa]

Using the "rough" calculations, based on power usage with 12 disks running 24/7 (again this is very rough averages)
My online Kw/h calculator shows I`ll be saving approx 1051.20 kWh/year, I've not worked it out in a financial sense, as I`m not concerned about the money, however, I do see your point. From a money perspective, not its probably not worth it at all, but trying to lower my own carbon footprint, every kW/h helps.
[edit]
I`ve just calculated the financial side of this, which based on the above figures is an actual saving of approx £126.23 (£10.51 per month) per year based on my current supplier's electrical costs per kW/h.
So no, from a financial point of view, this saving is completely marginal.

[edit2]
Summary, you know, I`ve just done some research on my smart meter, and accounting in this saving on a yearly basis, it's not even a 2% increase in my consumption on a yearly basis, so not even worth it in the slightest, even when looking into my carbon footprint. I`d get a bigger saving turning off 1 light strip from my back garden over a yearly period.
So scratch that..... I`m just going to by myself 2x 920watt platinum SQ power supplies instead which produce less heat and much quieter.
The carbon footprint side of things, I can do much more meaningful stuff at home to reduce this, which to be honest, surprises me. I`d have thought this would be quite significant overall since this is running 24/7. I`ve never actually done a detailed check on everything else thats running. I can get a bigger saving doing things like the following.
Reduce my fridge cooling down 1degree gives a bigger saving. Turning my TV off at the socket instead of standby is 1.5x the saving etc

 

[Chris Moore]

but trying to lower my own carbon footprint, every kW/h helps.

Based on the cost of electricity where I live, that works out to $52.55 for the year.
Not worth it... Not even for the carbon footprint. My electric bill is over $150 a month so , not a significant change there, and that works out to less than $5 a month. Less than the cost of a burger and fries at McDonald's.

So scratch that..... I`m just going to by myself 2x 920watt platinum SQ power supplies instead which produce less heat and much quieter.
The carbon footprint side of things, I can do much more meaningful stuff at home to reduce this, which to be honest, surprises me. I`d have thought this would be quite significant overall since this is running 24/7. I`ve never actually done a detailed check on everything else thats running. I can get a bigger saving doing things like the following.
Reduce my fridge cooling down 1degree gives a bigger saving. Turning my TV off at the socket instead of standby is 1.5x the saving etc

This is the reason I was suggesting that you look deeper. I wish that more people would figure this out.

 

[Inxsible]

I`m just going to by myself 2x 920watt platinum SQ power supplies instead

I thought you already had those included with the purchase of the server.

 

[Kiskaa]

I thought you already had those included with the purchase of the server.

It has the regular Plat rated 920w psu`s.
I`m going to replace them with the superquiet versions. (they generate less heat and are quieter)
I`ve seen a couple I get get on e-bay really cheap.

 

[Kiskaa]

Based on the cost of electricity where I live, that works out to $52.55 for the year.
Not worth it... Not even for the carbon footprint. My electric bill is over $150 a month so, not a significant change there, and that works out to less than $5 a month. Less than the cost of a burger and fries at McDonald's.

This is the reason I was suggesting that you look deeper. I wish that more people would figure this out.

It was never to do with my personal costs, it was to do with carbon footprint and heat generation. I couldn't care less about the running costs personally, within reason, but yeah, after digging, there are many many more effective ways to reduce carbon footprint outside of this (and easier to do too)

 

[Inxsible]

It has the regular Plat rated 920w psu`s.
I`m going to replace them with the superquiet versions. (they generate less heat and are quieter)

There are only 2 Supermicro 920W model #, afaik -- PWS-920P-SQ & PWS-920P-1R

What is the model number of the PSUs that you have?

 

[Kiskaa]

There are only 2 Supermicro 920W model #, afaik -- PWS-920P-SQ & PWS-920P-1R

What is the model number of the PSUs that you have?

Sorry for late reply.
The 2 included were the PWS-920P-1R model. The SQ being their quiet version, which I`m going to order.

Update btw, my new raid controller cards arrived, I`ve just installed them, and immediately my 6tb disks have been recognised. So all looking good now.
I can finally get on with setting up the new server :)
Thanks again for the help.

 

[hreda]

Is Broadcom NetXtreme-E 10Gb Ethernet supported on FreeNAS?
I have installed 11.1-STABLE successfully but cannot see it in ifconfig -a (displays only built-in cards). Mentioned in dmesg as No Driver Attached!

 

[Chris Moore]

Is Broadcom NetXtreme-E 10Gb Ethernet supported on FreeNAS?
I have installed 11.1-STABLE successfully but cannot see it in ifconfig -a (displays only built-in cards). Mentioned in dmesg as No Driver Attached!

Usually, when you have a hardware question, you would make your own thread instead of posting on another thread that appears to be unrelated to your question.
If the adapter is not recognized, it is either defective or not supported.

 

[hreda]

Thanks Chris, and apologies. I put my question here as it is first time for me to use FreeNAS Forums. I've already created new post for my question.
Thanks again and apologies...