Mark: You make many great points which require a lot of consideration. I’ll write some more posts about this issue in the near future, and I also have some plans for some tests to provide some more raw data about these issues.

Don, Albert, Mark, and MJ, thank you all for your comments. I’m proud of the fact that my blog is read by you and other people like you, and that you consider it worth the effort of writing such thoughtful comments.

- One of the difficulties (from a management point of view) is that a lot of this is about detail. Now detail isn’t bad, but it does make for lousy initiatives and bullet points, so it doesn’t present as well as ‘big bang’ items, like, say, consolidation or virtualisation. So, if what you really do is go round every server, examine load profiles, check memory sizing, check the possibilities for consolidation with others, the only thing there that your manager would be happy presenting upwards would be ‘consolidation’. Ho, hum.

- You are right that, at least on paper, a thin client approach can make very worthwhile savings against conventional desktop computing. Remember, however, that in practice you may well do two other, less desirable, things at the same time:

You will probably leave the host machine on 24/7 where with desktop machines they were probably only on for ‘office hours’ (whatever they were).

You may well move the server machine into the data centre. Air con may not have been critical in the general office environment (depending on building, climatic conditions, time of year, etc), but it almost certainly is in the data centre.

So, although there is a big potential gain from the thin client approach, it may not be as big as it looks at first blush.

Efficient power supplies.
Many cheap power supplies are really rather poor in a variety of ways, including power efficiency. The trouble is the way the market has developed, there seems to be little between the ‘cheap and cheerful – but don’t believe the spec’ bargain basement models and the ‘idiotic power output – look at the agressive protection grille’ gamers’ ones. Probably if you get your equipment from top rank suppliers – the HPs the Suns of this world – you can almost take for granted getting decent power supplies. From the less well known people, who knows? And you probably have five year old data centre equipment still doing the job it was designed for, but, back then, people didn’t take it so seriously, so the efficiency of that equipment is really unknown. Unless you go round doing testing.

(And you can probably add efficient UPSes to that.)

CRTs
I still have CRTs and I’m not going to throw them out while they still do the job (that would be un-green, but in a different way!), but you do have to be aware of the power wrinkles. While generally they use somewhat more operating power than the flat panel devices the bigger difference concerns standby. While a typical flat panel reduces power considerably when it blanks, if a CRT is on, it consumes a level of power that is close to the the active power. So the power switch is critical with CRTs.

And, of course, a monitor with a screen saver running is active, but banning screen savers is probably too joyless to contemplate just yet. Maybe a bit of user democracy is called for here – explain the trade-offs and see what the users think is correct behaviour. You may be surprised.

More modern cpus tend to consume less power for a given level of computational performance than older ones, so it can make great sense to consolidate onto more modern hardware. But, there is a danger here; if you take this to excess, you never have a settled system that ‘just works’. You are always moving processes and servers around and you are always having the unexpected little niggles associated with that. It may save you power, but irritates your users, which isn’t ideal.

The point about SSDs is interesting. I had been wondering about the possibilities of using an SSD for an external journal (and the performance implications of that), but put myself off the idea because of the wear-out implications. This may be worth following up, I don’t know. Even ‘more performance for the same watts’ can be green.

I also suspect that there are worthwhile gains to be made from storage architecture in many applications; starting from the bottom, file systems have an impact as do the drives themselves, RAID/non-RAID and NAS vs ‘local’ disks (and ability to spin down disks). But I can’t see me getting the time to do that experiment, either; at some point you just have to say that life’s just too short.

My suspicion is that a single, high performance, disk subsystem (raid, nas) beats a multitude of individual hard disks distributed about the individual servers, at least for usual load profiles, but there are also ‘single point of failure’ considerations which might make that undesirable. And its only a suspicion.

Don Marti wrote:
“Office workers don’t leave the electric pencil sharpener running, because it starts right up when you put the pencil in.”

While that’s true, it is also the case that electric pencil sharpeners don’t generally offer users the opportunity of leaving the motor running when inactive. When there is no pencil inserted, or the button isn’t pushed, they just don’t run. The IT industry has been less succesful in depriving end users of the option to do bad things. We expect to be able to have the choice of bad config options, and woe betide any supplier that doesn’t give us them.

And why have electric pencil sharpeners anyway? Is the use of a ‘plain ole’ mechanical pencil sharpener too much like hard work for modern office workers?

Albert Lash wrote:
“While I’m glad computer chip manufacturers are working to produce more energy efficient chips, I hope that they are able to reduce the heat dissipation of them as well. While the two seem to go hand in hand (i.e. – if the chip uses less power, it should generate less heat), I’ve found a variety of situations where it doesn’t always add up.”

While I agree with you that the attempts by chip makers to reduce watts per unit of computation are good, I haven’t followed the point about “if the chip uses less power, it should generate less heat” being other than universally applicable – surely that’s always true: If watts go in, they get disspated somewhere (exactly where might be a bit obscure in, say, PoE, but the result is dissipation somewhere). Anything else would violate conservation of energy.

(Oh, and an optical pyrometer is a useful tool for a quick look around to see what is getting hot. And while temperature and power dissipation are not the same thing, it does give you a pointer to where you ought to be expending your efforts and to local hot-spots.)

I agree about booting. Having machines boot quickly is a good feature and apparently SSDs support faster boots as do newer OS features such as “upstart” (in theory even if not yet in practice). But I still think that booting machines automatically at 8AM is not going to significantly increase power use and will provide a benefit.

Albert: For air-conditioning systems for homes you typically expect to see about 1/3 of the energy required for cooling. So if you want to remove 3000J of heat energy from a room then you need 1000J of electrical energy. If the A/C systems for server rooms run at the same efficiency then you merely add 1/3 to the power use. But given the technical challenges of providing such large amounts of very cold air in a small space it seems likely that the efficiency is lower. But I don’t have any numbers.

Good point about SSD, I had entirely forgotten about them while writing this post.

Also that’s an interesting link about Japan. More appropriate office clothing is a good idea.

http://www.npr.org/templates/story/story.php?storyId=14024250

While I’m glad computer chip manufacturers are working to produce more energy efficient chips, I hope that they are able to reduce the heat dissipation of them as well. While the two seem to go hand in hand (i.e. – if the chip uses less power, it should generate less heat), I’ve found a variety of situations where it doesn’t always add up.

Solid state drives can purportedly decrease boot up time and improve system responsiveness, and for corporations that use SANs, they are more than enough for workstations to boot from. Using SSDs instead of hard drives should also reduce heat dissipation.

I feel we’re at a critical junction for hard drives and SSDs – you really need at least 2GB of storage for an operable OS (though much less is definitely doable), and its now possible to get 2 and 4GB chips for less than the cost of small hard drives. Granted they are 10X the size of the chip, but how often to corporate users need access to that much storage locally?

Good posts about the EEE – ACER just came out with an ATOM netbook too!