Web Hosting Talk : Web Hosting Main Forums : Colocation and Data Centers : Power consumption

[supremehosting]

Hi Guys, Im looking to get some feedback on the power consumption of our servers prior to installation.
We have a half rack with a power allocation of 8amps. Were planning to run dual core Optrons, obviously
we need to get the most from the space and were planning to use each rack space.

CPU: Dual Core Dual Opteron 270' (WITH 1MB of L2 Cache on each core.)
Chassis: 1U Supermicro
Memory: 4GB DDR
Storage: 4x 160GB WD SATA RAID5

Some of the servers will be dedicated to mail, others to DNS, actual web content, and others to database.

1) How much power do you think well require during the boot process for these servers.

2) For these servers to run close to capacity during peak hours, what do you think our power consumption will be per half rack.

[Mfjp]

1) During the boot process, expect about 4amps to start up.
2) After boot up, each server of this type would draw about 2 to 2.5amps each. We have a similar system with 2 x 146GB 10K hdd, and they do about 2.2 when booted up.

[supremehosting]

Originally Posted by Mfjp

1) During the boot process, expect about 4amps to start up.
2) After boot up, each server of this type would draw about 2 to 2.5amps each. We have a similar system with 2 x 146GB 10K hdd, and they do about 2.2 when booted up.

Have you had times where your available power was not enough to meet the 2.2amp requirement, if so how did the servers function.

[porcupine]

Originally Posted by supremehosting

Have you had times where your available power was not enough to meet the 2.2amp requirement, if so how did the servers function.

You'll simply blow the circuit breaker the servers are on, and the circuit will thus be shut down

[supremehosting]

Do the agree with the power requirements stated above.

[porcupine]

Originally Posted by supremehosting

Do the agree with the power requirements stated above.

Sustained power consumption of 2.5A for a quad (dual dual core) opteron 270 system with 4x sata drives is fairly reasonable. We have a customer with a cabinet full of 265's with 2 x 10k rpm raptor drives per system, they drive a *little* bit less then 2.5A/ea running, but are also fairly underutilized in terms of load.

[RoryErickson]

I would budget for at minimum 3A during bootup and ~2.5A during normal operation. That is, don't boot everything up at once if you're at your upper limit for the circuit.


A couple other items to remember however, and these are very important.

- Circuits don't really come as 8Amps, so you're likely going to be on a shared 15A or 20A circuit. That means you may or may not have someone else on the circuit who could be using more or less of their half allotment. Could work to your benefit or not.
- As an electrical code you never use your entire circuit, you use 80%. That means you don't have 8Amps available, you have 6.4Amps. Using more means your circuit is more prone to trip and is also more likely to fail pre-maturely--circuits over 80% sustained usage are prone to damage due to heat.

[timdorr]

Well, it also depends on how much usage you expect on those systems. We're doing 1.6A-2A on systems with very similar specs, just SCSI drives instead of SATA.

[jimmy]

Originally Posted by RoryErickson

- Circuits don't really come as 8Amps, so you're likely going to be on a shared 15A or 20A circuit. That means you may or may not have someone else on the circuit who could be using more or less of their half allotment. Could work to your benefit or not.
- As an electrical code you never use your entire circuit, you use 80%. That means you don't have 8 Amps available, you have 6.4Amps. Using more means your circuit is more prone to trip and is also more likely to fail pre-maturely--circuits over 80% sustained usage are prone to damage due to heat.

I second Rory's statement on the first part. However, on the second part, I am pretty sure that you can use the whole 8 amps for a 1/2 rack because a regular cabinet usually comes with 20 amp of power @ 120v. So a half rack will usually comes with 10 amp of power and at 80% utilization (fire code), that will give you a usable of 8 amps. (check with your provider to make sure weather the 8 amps is net or gross utilization)

If you have access to the server and can monitor the power usage before putting your server online, you can consider using kill a watt device as seen here: http://www.thinkgeek.com/homeoffice/gear/7657/
This will give you the amperage of your server utilization.

[RoryErickson]

Originally Posted by jimmy

I second Rory's statement on the first part. However, on the second part, I am pretty sure that you can use the whole 8 amps for a 1/2 rack because a regular cabinet usually comes with 20 amp of power @ 120v. So a half rack will usually comes with 10 amp of power and at 80% utilization (fire code), that will give you a usable of 8 amps. (check with your provider to make sure weather the 8 amps is net or gross utilization)

If you have access to the server and can monitor the power usage before putting your server online, you can consider using kill a watt device as seen here: http://www.thinkgeek.com/homeoffice/gear/7657/
This will give you the amperage of your server utilization.

It's a good point that they may have brought a 20A circuit to the full cabinet and have already calculated for the 80% utilization, I suppose the only way to know for sure would be to ask them.

If you want to know your usage at all times, you could even go for an APC Zero-U Metered Rack PDU. They're not 100% accurate, but would be close enough for your purposes.


- Rory