I’ve always kept my computers up’n’running day and night although they are mostly idle during the time I sleep or labour at work.
I’m too lazy to shutdown the whole thing few times a day and then but the electricity bill is getting quite big, so I started to think about suspending the computer.
Of course the whole suspend feature has been used in laptops for ages but I guess not that much in Linux workstations. Occasionally I need to access my workstation remotely but that’s why there’s wake-on-lan and I still have my firewall computer always running.
I installed a package called hibernate and configured it a bit to suspend to RAM instead of suspending to disk. It takes only a few seconds to come up from the suspended state and I have all my windows right where I left them. Only the network connections get cut off, which is a bit annoying as I use SSH for certain things. There have been one or two occasions during the over a hundred suspends I’ve done so far, where the workstation hasn’t come up without extra kicking.
I measured the power consumption of two workstations with two different energy meters. One is a proper one from the electric company and one is a cheap one from a local store.
I conducted one to three measurements for each state and in the table below are the typical values.
| Computer | State | W (Good meter) | W (Cheap meter) |
|---|---|---|---|
| 1 | Idle | 55 | 65 |
| 1 | Suspend | 2 | 23 |
| 1 | Off | 1 | 23 |
| 2 | Idle | 98 | 87 |
| 2 | Suspend | 2 | 21 |
| 2 | off | 1 | 19 |
Based on these results, you do save some power by suspending the computer (and the cheap meter is close to useless). The actual amount of saved electricity depends on the total consumption in the idle state. Newer computers have decent power management and my workstation doubles the consumption from 100W to over 200W when I e.g. start an 3D game.