Hot answers tagged power
31
Before the outage:
Power everything off - workstations, servers, printers, switches, the works.
Turn off your UPS' so they don't panic when power is lost.
After outage in this order:
Turn on UPS
Turn on networking (router, switches etc)
Turn on servers
Turn on workstations
Turn on everything else
Have a test plan ready so you can test important ...
31
You can also get short Y power cords.
These cables (including the single variety) are sometimes called "outlet savers".
I also love the 90° rotating plug variety for some applications. The cord goes flat against a wall.
27
Having had some 'discussions' with the inspector that comes around our offices once a year to make sure we're not being bad, I have a better idea as to what code says about this. Paraphrased from said inspector:
Thou shalt not plug a power-strip into another power-strip Nor any multi-outlet device into another multi-outlet device, for it is a fire-hazard, ...
21
You can plug in that many drives via USB . . . but I wouldn't recommend it. The single biggest issue you're going to run into is the use of USB 2.0 (480Mb/sec shared across all devices on the controller). Unless you're using USB 3.0, you are going to seriously limit your disk throughput.
USB was intended for temporary (hot plug) or situations where very ...
18
I think the official name is "Power Strip Liberator".
Google image check: http://www.google.com/images?q=power+strip+liberator
UPDATE:
Sorry, I think that's a product's name (trademark), not the common name for the "thingy." But I looks like that the product is the "Coke" amongst power extension cords. :)
15
I've never used them because they're a single point of failure, at best.
Every server I deploy into a real datacenter has each PSU plugged into a different PDU in the rack, each of which are attached to a different independent UPS, on different circuits, ideally even fed from different power feeds.
If the UPS, PDU or circuit your Y-cable's attached to goes ...
14
You might want to distinguish between filtered power and uninterrupted power. Uninterrupted power is probably a good idea for things that you want to shutdown gracefully. Depending on your needs you might only need enough time for the shutdown to finish, resulting in a much cheaper UPS. Other devices may not need UPS at all, but only filtered power. ...
12
Horizontal PDUs are a mess -- In my experience there's nothing that can be done to make these neat: You can bundle your cables neatly down the side of your rack, but when you get to the PDU they fan out into a rat's nest.
For vertical ("Zero-U") PDUs you can acquire custom-length power cables (they're available from various suppliers, usually in the same ...
11
Having just done through a datacenter shutdown in the last week, this is fresh on my mind ;). Yes, shutting everything down needs to be done. Some things can tolerate having the power yanked out from underneath them, and they typically can be identified by not having a power switch on them. Depending on what the heck the facilities people are doing, you may ...
11
This is because that equipment was designed to be installed anywhere in the world, and not every place has 3-wire electrical. Additionally, not every 3-wire install has a well grounded ground-wire, so having the option of creating a separate ground is a very good idea for the enterprising electronics manufacturer.
What is the impact of not using the ...
10
Start with the power. It will pretty easily show you how much of everything else you need.
Get a number, maybe ask the electricians, of how many KW or KVA the project is.
If it's less than say 12 KW, you are talking a medium size build out. Few racks, say five, a hundred or so servers.
100 * (1 amperes) * (120 volts) = 12 000 watts = 12KW
Account for ...
10
In my experience yes. The main problem is that often too many devices are left turned on and create quite a peak when power is back again, with potential damaging effects for the power supplies.
This is the reason why intelligent PDU for server racks often turn devices on in a staggered mode after a power loss.
10
My friend an I have a small software development business.
From this I gather that you're not in the infrastructure business.
They can consume upwards or 2KW peak power. We may host upwards of 3
or 4 of them
From this I gather that your power needs are beyond a small office's normal abilities.
Then there would be air conditioning and other ...
10
You can use the PowerCfg utility to find out. It's part of Vista, no need to download it.
powercfg -lastwake
Will tell you what woke up your laptop.
To see all devices that can wake your computer, try:
powercfg -devicequery wake_armed
You can turn all these devices off with Device Manager, on the Power Management tab. Unselect "Allow this device to ...
10
I have seen some very, very bad server interactions when you plug a UPS into another UPS, and run a server off it.
In our specific case, the server had a clock that ran ridiculously fast, as in, it would gain 5+ secs per hour. Removing the "double UPS" fixed this.
Granted this is not exactly what you're describing, but I would say based on my experience ...
9
It is called a pigtail extension cord. http://www.mockett.com/furniture-hardware/technology-into-furniture-integration/power-communication-systems/plastic/pt1-90.html
9
Pulling the power causes everything to stop in flight, with no warning. kill -9 has the same effect on a single process, forcefully terminating it with a SIGKILL.
If a process is killed by kernel or power outage, it doesn't do any clean-up. That means you could have half-written files, inconsistent states, or lost caches. You usually don't have to worry ...
8
I use the HP Power Advisor and the APC UPS Selector tool to provide a good estimate of power requirements. The APC tool has a great database of common telco/server equipment, and provides a way to build in some headroom for expansion.
8
Flywheels are used in large data centers to cover short power gaps like yours, or to allow time for a backup generator to come on line. They are (typically) only good for 45-60 seconds, and they are expensive, but they have a longer lifetime than UPS batteries, and can make sense for a very large data center.
Another approach was Google's, who integrated a ...
8
There is at least one solution - IEC Lock - that I'm aware of. I think it's based on some kind of spring-friction mechanism and fits existing sockets. I haven't personally seen the need to try any locking solutions, so YMMV.
Places selling those can be found e.g. searching with Google. Prices are around 3-4 USD, so I'd say it's relatively cheap.
8
The primary reason such items are frowned upon is due to redundancy, lack-thereof. Using such a cable means all of your server's power-inputs are being fed by the same circuit so when that circuit dies (or the PDU it's connected to, I've had that happen) so does the server. Colos strongly recommend Primary and Secondary circuits for just this reason and want ...
8
Yes, blades are dense. :)
You need to use a power budgeting tool to determine maximum power draw of your particular hardware configuration. Your reseller should be helping you with this. (since that's what I do :)
Multiple power supplies can have quite a few possible scenarios:
N+N configuration: Maximum power draw of N×Wattage power.
N+1 configuration: ...
7
Your understanding is correct: In modern servers power supplies are what is referred to as "Parallel Redundant" - Both power supplies are active, and both are supplying power to the system bus.
In the event of a power supply failure (internal fault, loss of input power, etc.) the remaining power supply (or power supplies) will need to supply additional ...
7
Mounting them is not the problem: It's going to be as slow as hell.
USB performance for external harddrives sucks at the best of times anyway.
Everything on the same USB controller/hub shares the bandwidth.
You will have to spread them out over as many separate USB controllers as possible.
Most motherboards only have 1 or 2 controllers so you will have to ...
7
Promoting my comment to an answer...
Does anyone have anything that shows what agency this is (NEMA?) and these actual regulations?
This requirement comes from the National Electric Code, which is published by the National Fire Protection Association
National Electric Code requires that the continuous currentNote 1 drawn from a branch circuit not ...
7
What are the advantages of using 48V DC over 230VAC or 415VAC 3phase
Efficienty and heat.
There is no AC/DC transformation in the server. Yes, you have one large converter, but it is not in your rack - so you produce less heat in the rack.
Efficiency. Large converters ?= more efficient. This gets really nice when you talk UPC - battery power is DC ...
7
I'm not sure about servers, but the current thinking in embedded devices is not to bother with steps between low-power and flat-out because the extra time involved will eat your power savings, so basically they run low power until they get any real amount of cpu load at which point they flip over to fastest-possible so they can finish the job and get back ...
7
Your options are:
UPSes
laptops
Google-style batteries and custom motherboards[1]
Crazy flywheels[2]
Basically you'll need batteries somewhere to cover even a couple of seconds of power outage, or a huge spinning slab of something heavy which you can generate energy from in a hurry.
UPSes aren't that expensive, and look even cheaper when you consider ...
7
The efficiency improvements you get from moving to 110v to 220v are not that great. Yes, there is less heat, but we're talking a few percentage points. The few things I've seen, generally in commodity hardware not server hardware, show efficiencies moving from 83% to 86% efficient, or +3% efficiency. That can add up if you have a 10K sq/ft room full of ...
7
You are getting the same amount of 'power' either way (120V x 60A = 240V x 30A), so from an electrical "power" standpoint it is a wash--either one will support the same amount of equipment in the rack...
You should do some research to be certain, but most modern computer equipment is equiped with switching power supplies that accommodate a wide range of ...
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