You are taking a risk, having 24 disks in one JBOD.
My understanding of a JBOD RAID is that if any of the disks fails, you lose the entire array (you lose it all).
By “JBOD”, I assumed that you meant an array. Or did you mean “just a bunch of individually connected disks”, not part of an array?
It has to do with how many watts will be passed through the connection points for the splitters. Heat is the issue and you will melt the wires.
No, that is what an electrician or Google will tell you.
“What is the maximum allowable continuous amp load on a 20 amp circuit?”
“Because the load is continuous, multiply 600 volt-amperes by 125 percent (600 x 125 percent = 750 volt-amperes). A 20-ampere, 120-volt branch circuit will carry 2,400 volt-amperes (20 x 120 = 2,400). The maximum number permitted on a 20-ampere branch circuit is three (2,400 ÷ 750 = 3.2 = 3).”
If you ignore this rule your risk of fire goes up dramatically.
I didn’t question your assertion about those fuses. We agree on that.
What I wanted to say is that the logic that applies to those fuses is not what applies to those PSUs, as those two are different animals. PSUs are meant to handle 100% load at 24/7 without any hazards. However, what that 100% is, is not the sum of Watts on all rails (thus the sum of Watts on all connected equipment).
“Good brands have headroom for “100%” load and can do it just fine. The problem is PSU designs efficiency maxes around 70-80% load. Technically if you want to punish your psu you can. If you thing burning your house down is worth the risk, go ahead.Jan. 21, 2018”
You will melt the connectors like that! (or the cables)
Here’s the thing. hdd’s use the 5V rail as well as the 12V rail
1200W PSU has most of it’s power on the 12V rail, maximum 30A on the 5V (typically 25A)
HDD can use about 0,9A on 5V and 1,5A on 12V (check the specs)
So you will overload the PSU for sure with 120 hdd’s
Also 4-pin Molex connector and PSU connector can handle max 156W
Sata connector can only handle 56W total power
(this is 12V + 5V combined)
Long story short you need a way to turn 12V into 5V, see link below for an example.
And then still 120 hdd is too much because the power draw will be 1200W with everything running at minimal, during spin-up of the drives the PSU will shut-down.
here’s an overview
This guy has a good workaround
JBOD is not RAID
JBOD = Just a Bunch of Disks.
That is not true. Take a look at “What do Bronze, SIlver, … ratings mean?” section, and check values for Titanium certification. It is up to 94% at 100% load. Again, PSU with one sticker is not the same as with another. Also, from brand A is not the same as from brand B. As we already stated some time ago, saving on PSU quality is potentially the worst one can do, overestimating what it can deliver (thus underestimating the load) is another bad thing to do.
Kudos to Voodoo for finding a real world answer. I thought the most relevant quote form Voodoo’s link to the question that stated this thread is below:
So AlexXXL With enderTown’s example, I would say that you could barely power your 120 HDDs with two 1200 watt server quality PSUs. I would go with two 1500 watt server quality PSUs to be safe and solid. This also assumes that you a safe wiring setup
If you do go with another 100 HDDs I would add two more 1500 watt PSUs and spread the power equally.
That describes efficiency ratings and has nothing to do with whether a device performs well running at 100% constantly.
"What percentage should PSU run at?
Moreover, you should keep in mind that the sweet efficiency spot is usually around 40-50% of the PSU’s max-rated capacity. That and the closest a given power supply is to its max load output, the lowest the efficiency.Apr. 21, 2021"
or this
or this
https://pcpartpicker.com/forums/topic/77606-how-much-extra-wattage-should-a-psu-have
and many other articles, guides, and even manufacturer recommendations will say the same.
High End power supplies will run safely, full time, at their max rated PSU but it WILL shorten their life doing so. Low end PSUs can literally catch on fire if left on 24/7/365 at full load with maybe a bit too much dust or a weak solder connection.
Most recommend that if you do not want to shorten the life of your PSU you should run full time at no more than 50-70% capacity and any PSU is more subject to failure and/or fire if run at max capacity constantly.
With a server grade PSU I would run full time at or near 100% capacity if I were not concerned about its lifetime but I would prefer to use under 70%. In any case of a full time hard working PSU I would take care to keep my PSU clean, cool, and regularly inspected.
We don’t have to argue, but putting 120 HDD on a PSU will most certainly blow the +12v and +5v rails. That is a fact. The 80+ ratings are only efficiency guidelines at continuous load. It doesn’t say anything about burst loads. Besides, if, for example, you put 1000w of load on a 1200w PSU, burst loads will almost certainly exceed 1200w and destroy the PSU.
how do you assign drive letters with that many drives. I’ve been using NAS in raid to limit my drive letter usage. thanks matthewjbauer. Found this link if anyone is interested . How to mount hard drive as folder on Windows 10 | Windows Central
You don’t. At least in Windows, you create an NTFS folder and mount the logical folder as a physical drive.
Thank you. I appreciate you insight into my problem.
It depends on how those disks are connected to your controller:
From wikipedia:
There is a pertinent paragraph that reads:
" JBOD[edit]
JBOD (abbreviated from “Just a Bunch Of Disks”/“Just a Bunch Of Drives”) is an architecture using multiple hard drives exposed as individual devices. Hard drives may be treated independently or may be combined into one or more logical volumes using a volume manager like LVM or mdadm, or a device-spanning filesystem like btrfs; such volumes are usually called “spanned” or “linear | SPAN | BIG”.[2][3][4] A spanned volume provides no redundancy, so failure of a single hard drive amounts to failure of the whole logical volume.[5][6] Redundancy for resilience and/or bandwidth improvement may be provided, in software, at a higher level."
The key words are:
“…so failure of a single hard drive amounts to failure of the whole logical volume…”
So it depends on how user rfc2324 set up his JBOD, which is why I commented with the potential risk.
Cheers!
sure, but that goes for any hdd’s you have attached to a computer.
I would say the key phrase of jbod is:
“is an architecture using multiple hard drives exposed as individual devices”
Unless you specifically choose to use Raid(like) software of controller to create a spanned volume, it is just what it says it is, a bunch of disks.
There is no inherent risk of using a Jbod disk rack, there is an inherent risk of using spanned volumes without redundancy,
The “risk” depends on the value of what needs to be protected. There is no value in plots, except replotting times. As such for hosting plots (spanned or RAIDed), if one doesn’t have redundancy, replotting time is potentially a long one. On the other hand, with redundancy, the cost of replotting one failed drive is much lower than the revenue lost due to redundancy. Either way, spanned or RAID architecture is not the best solution for hosting plots (IMO).
Good post. Just to make sure, I have the specs of the mentioned PSU:
|+5V|25A|
|+3,3V|25A|
|+5V & +3,3V combined|150W|
|+12V1|104A|
|+12V2|-|
|+12V1, +12V2 combined|1248W|
I will need the specs for the HDDs to calculate the power needed according to the specs. I will have them tomorrow and post here the results. But even without the specs, I can see that I have 150W for 3v+5V, so if the drive needs 3-5W from a 5V source, I have between 30-50 HDDs on this supply.
Plus, I have read recently that on most modern PSUs, 12V and 5V are coming from same “source”, meaning 5V is provided by lowering the V from 12V to 5V. This maybe means that I can be pretty comfortable regarding the 5V power needs, if that is the case with my supply, of course.
Well can we calculate this together?
If normal power usage of a hdd is less than 10W, each molex to 5 x sata adater will have to endure less than 50W, which is quite real. The real problem us the connector on the PSU which by this math will have to endure eather 3x molex to 5 x sata, which means less than 150W or more, if I put cables with more molex to 5 x sata converters, like 4-6 of them.
I have certain experience with GPU mining and can tell you that PSUs can work 24/7 on 90% load or even more in some cases. For months, if not for years.