DDR3 vs DDR4 memory (ECC) for FreeNAS

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#1
For normal desktop environment, there are hardly any scenarios where there is a noticeable performance gain from going with DDR4 over DDR3 memory. This is mainly due to the timing latency increasing, almost nullifying the increased bandwidth of ddr4 speeds.

I'm wondering if the same thing applies in a FreeNAS setup. I'm about to start my first build, but wondering if I should build it around the newer ddr4 platform, or just save a tad and stick with a ddr3 platform. Would the faster ddr4 for caching have a measurable difference over ddr3 ECC memory?
 
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#2
Performance will not be affected. Either platform will be supported. I chose to go with ddr4 with my new build because I will be upgrading the ram in the future and ddr3 might be limited at that time.
 

jgreco

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#3
The speed of your NAS is primarily limited by the 1Gbps ethernet (or 10Gbps ethernet). RAM is so much faster than that.
 

nightshade00013

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#4
Agreed, drive speed and Lan speed will be your biggest bottlenecks. The only time you may see a little improvement is if you are running a VM and even then I doubt you will notice. Well and when you are memtesting it you might shave some time off too.
 

diskdiddler

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#5
While DDR4 normal memory is becoming quite reasonable in price, I would imagine boards that are capable of taking ECC DDR4 and the ECC DDR4 modules themselves, would still be fairly rare, surely?
I think we've got another year before DDR3 becomes kinda rare stuff.
 

Ericloewe

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#6
While DDR4 normal memory is becoming quite reasonable in price, I would imagine boards that are capable of taking ECC DDR4 and the ECC DDR4 modules themselves, would still be fairly rare, surely?
No. LGA2011-3 stuff has been out for a year. And people who buy that also tend to buy truckloads of RAM. Plus, Skylake is here, with Xeon E3 v5 just around the corner.

think we've got another year before DDR3 becomes kinda rare stuff.
Probably longer. DDR3 will be available at reasonable prices for at least a year and a half, probably. It'll be easily available for a few more years, at less reasonable prices.
 

jgreco

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#7
The 2011-3 stuff is great. 128GB of RAM for less than a thousand bucks.
 

pro lamer

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#8
Can DDR4 performance boost be a gain in terms of snapshots?

I am a noob and I am planning a future proof rig so I can upgrade only those component that I really need. I am new to backup plans too. I think I may have 64-128GB RAM in future (EDIT: 64-128 per rig and one or two rigs - I guess that's what I may afford) and lots of snapshots.

I am considering a second hand Xeon E5 v2 (socket R aka 2011) cos of its low price but it supports DDR3 only.
 
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Ericloewe

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#9

pro lamer

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#10
Snapshot listing does get complicated with many snapshots, but that's a disk IOPS limitation.
Thanks, this answer seems to address my other concern, too. I thought that if I had lots of RAM then FreeNAS might cache snapshot metadata for listing snapshots but even if it did that (what I don't know) since I find IOPS similar to CAS Latency then count of RAM MHz would be no help to me because CAS Latency is told to be the same among DDR3 and DDR4 in terms of nanoseconds http://www.crucial.com/usa/en/memory-performance-speed-latency)
 

Stux

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#11
DDR3 and DDR4 essentially have the same latency. As the bandwidth increases the frequency increases, and the amount of ticks in a wait state is thus increased to compensate so the overrall latency stays the same.

It is most likely your performance will be disk bound, network bound, or amount of memory bound, not memory bandwidth bound.

And DDR3 can be had second hand cheaper than DDR4, which is crazy expensive at the moment.
 
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pro lamer

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#12
amount of memory bound
DDR3 can be had second hand cheaper
Now it seems pretty simple (ceteris paribus or mutatis mutandis) - one can buy more gigabytes of DDR3 than DDR4 for the same amount of money thus moving the memory amount limit/bound further :)

EDIT: ceteris paribus or mutatis mutandis - I don't know which phrase suits better since my Latin command is very poor. I meant that one may take some other factors into account e.g. whether prices of DDR3 go higher in future or what to do when a motherboard has a malfunction (fix it or replace with a new one... and whether ECC DDR3 motherboards are available in future and if not and cannot be fixed - sell the DIMMs? for what price?)
 
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