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12396
August 31st, 2006 12:00
Rack power question
hey all, New to the forums here.
Got a couple questions about powering up racks properly. I have just finished reading "Dell Rack Engineering RapidPower PDU Best Practices" to see how they suggest to power racks. After reading this I realized that our racks are not powered like this document suggests or even close to it for that matter.
We have 3 Dell racks filled with Dell PE servers, and 2 tape servers. The servers range from 1U to 4U, old and new. We have all the servers going into APC 1500 SmartUPS (4 per rack) and then the UPS' plug into a PDU that plugs into the wall.
Do you forum users adhere to plugging your servers into rack mounted PDUs and then the PDUs into UPS' and the UPS into the wall? If so, do you have variying kinds of PDUs for the different amperage requirements of your servers? And do you have each UPS plugging into a separate locking plug in the wall?
Sorry if this sounds so beginner, we just got burned by our "strategy" because we had several UPS' with bad batteries that management held off on fixing only to add one more server and then find that the PDU turned off because too much load leading to a lousy morning..
-Adam
Got a couple questions about powering up racks properly. I have just finished reading "Dell Rack Engineering RapidPower PDU Best Practices" to see how they suggest to power racks. After reading this I realized that our racks are not powered like this document suggests or even close to it for that matter.
We have 3 Dell racks filled with Dell PE servers, and 2 tape servers. The servers range from 1U to 4U, old and new. We have all the servers going into APC 1500 SmartUPS (4 per rack) and then the UPS' plug into a PDU that plugs into the wall.
Do you forum users adhere to plugging your servers into rack mounted PDUs and then the PDUs into UPS' and the UPS into the wall? If so, do you have variying kinds of PDUs for the different amperage requirements of your servers? And do you have each UPS plugging into a separate locking plug in the wall?
Sorry if this sounds so beginner, we just got burned by our "strategy" because we had several UPS' with bad batteries that management held off on fixing only to add one more server and then find that the PDU turned off because too much load leading to a lousy morning..
-Adam
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jeffy210
33 Posts
0
September 7th, 2006 14:00
2 Dell Racks
Rack 1:
- PE 6450 (x2)
- PE 6650
- PE 2550 (x3)
- PE 1850 (x2)
- PV 660F
- PV 224F
- PV 51F (x2)
- PV 120T
Rack 2:
- KVM
- PE 1550
- APC Symetra-LX (16kVa)
In each of the racks We had 4 PDU's (two on each side), from there We ran each of the PDUs into a seperate backplate on the UPS. Since most all of the servers have 2 power supplies we would run each one to a seperate PDU. Single PS units were divided between the remaining PDU's to balance the load.
Basically this reduced any single point of failure. If a PDU went out, the server would switch to the other PDU, if a backplate went out, again it would switch. The Symetra is redundant itself if power supplies or batteries go out.
Baring a Symetra, if you are using multiple 1500's, you should be fine as long as you divide things back to the wall (if you can have each UPS on a seperate breaker, even better). The biggest thing to remeber is divide things up so that you don't have a single point of failure, that is what matters the most
compaqfan
13 Posts
0
September 8th, 2006 14:00
I agree with Jeffy. I not familiar with your facilities so it's kind of hard to plan for your installation but there are two basic things you want to consider:
1. Plan for total redundancy if your facilities allow.
2. Do not overload your UPS(s) or circuits.
Generally if I do not buy an APC Symetra for a rack, I'll purchase (2) 3000VA UPS and feed them from 2 separate panels in our datacenter. Working from there back to the server, each UPS will feed it's own PDUs in the rack and then 2 separate PDUs will feed each power supply in the server. Total redundancy from the server's power supply back to the power source for the building. If you buy a Symetra, it has redundant power modules, logic modules, and you can plan for extra battery capacity. Though I will warn you that out of the 4 6kva Symetras we have, one has failed and brought the whole cabinet down. Both logic modules failed and shut the rack down... so much for redundancy. We were able to get the rack running again by putting in bypass mode and luckily all dual fed servers in the rack were fed from an adjacent Symetra in another rack. :smileywink: (Good planning on my part!)
I would check out Dell's online Datacenter Capacity Planner to get an idea of how much power you will be using. It's not perfect, but it's a good start and from my experience they err on the side of caution and estimate a fully loaded server. Usually you'll use less power than they state.
The "Dell Rack Engineering RapidPower PDU Best Practices" is also a great document to keep on hand. I'd also recommend you familiarize yourself with the different NEMA 110/220v power cables, plugs and receptacles that are available for future planning. Nothing is more frustrating than ordering the wrong PDUs for the type of servers you're installing.
BTW - always plug your PDUs into the UPS and then the UPS into your building power.