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Energy efficient rack server questions

alexd

Administrator
Staff member
I am going to replace our database server this year and I am looking for something more energy efficient. I have some questions... How is power usage calculated in servers (and other electronic equipment)?

I understand that all the components in a computer use power and that newer servers use less power hungry components (2.5" drives, lower voltage CPUs, etc), but doesn't it all boil down to how much power the power supply(s) are drawing off the grid?

If I get a server with redundant power supplies (like we currently use), aren't both power supplies drawing power at the same time and doesn't that cancel out any power saving?
 

Dr. Grinch

TRIBE Member
Power consumption in servers is measured at idle (0% CPU load) and at load (80+% CPU load) + disk activity.
Your power supplies have a peak amount of power they are capable of delivering.
Redundant power supply configurations vary from server to server. Some servers will have up to 4 PSUs installed, with only 2 or 3 active at once, and one waiting to failover. Most typically have 2 that are always "live", but are splitting the load dynamically. If one fails then the other picks up the remaining load.

Your challenge with replacing a DB server is that you probably need a large amount of storage, and significant CPU/RAM to deal with the requests.
It's hard to save power there, because replacing a large array with SSD drives is very expensive, and you will need a hefty CPU still to handle the workload.
Upgrading from your older server to todays newest tech might yield you 30% power savings in the CPU/RAM, but your disk array will still suck back the power.
 

alexd

Administrator
Staff member
Your challenge with replacing a DB server is that you probably need a large amount of storage, and significant CPU/RAM to deal with the requests.
It's hard to save power there, because replacing a large array with SSD drives is very expensive, and you will need a hefty CPU still to handle the workload.
Upgrading from your older server to todays newest tech might yield you 30% power savings in the CPU/RAM, but your disk array will still suck back the power.
I will be using 15k 2.5" SAS drives. Do the smaller drives use less energy than the full size SCSI drives we have been using?

Also, I am looking at a pair of quad core Xeons (probably a pair of 5560 CPUs). Don't they also cut back on power useage when they are not under heavy load?
 
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