Building 1U Rails Server - Power Calculations?

Rails Deployment
1

Hi all,

With all the mini-apps i’m writing I’ve decided to build my own 1U rack
server, but need a few pointers on calculating power consumption.

Basically the colocation place i’ve selected for the device has a limit
of 0.5 Amps of power per box, so need to keep the power down below that
limit otherwise it’ll cost more to host.

A friend of mine is doing the same, I can build and setup the system
myself but never mastered power calculations at school so a bit alien to
me working out power load, etc. :wink:

I’m going to be using something like…

CPU:
AMD 64 chip [heard they’re good for lower power + speed]

O/S:
Fedora 8 [works well with AMD cpu’s low-power state]

HDD:
2x SATA2 WD Drives [500gb each, in a RAID 1 config]

MEMORY:
2x 2GB sticks [samsung brand, been using then all the time, reliable]

MOTHERBOARD:
ASUS standard ATX mb [always found ASUS reliable]

Case-wise I’ve found a couple on ebay so will try and snag one this
week.

PSU:
hunting around for good reliable PSU, but most only operate at 50-60%
capacity, sort of wanting it running at 80% if i can.

The company I’ve chosen is http://www.rapidswitch.com/ up the road from
where I live, £32 a month (which is less than the $100+ dollars i’m
paying my current colo to run my virtual boxes, and I’m kinda looking
forward to doing this myself).

Gotta keep it down to 0.5A

Any ideas how to do the power calculations greatfully received,

2

Ok, using DELL’s power calculator I worked out…

0.5A => 120Watts.

so a nice bit of legroom, now hardware?

3

for me, it’d probably be about 5 rails sites with about 7 mongrel
clusters spread over these, then a php website my fiancee’s building for
a friend at work, and then probably a load more.

as this’d give me a server with less limits than your average setup from
the third-party and total control so i could get it exactly how i want
it, the flexibility and extra experience would be pretty invaluable;
hence the decision.

hope this helps.

4

Something to keep note is:

More RAM = more juice…

7 mongrel clusters is a minimum of 1.5 GB of ram, right? (with
headroom)
You’d want a little more for the system - db etc.

120 watts isn’t a stupid amount of power by any stretch…

On Mar 2, 6:30 am, John G. [email protected]

5

couldn’t agree more, that’s why i’m researching like mad to get things
right first time.

looks like most things will be a custom job, will let you know how it
goes.

All the best,

John.

6

Just curious: How many "mini-apps? How much traffic? What is your
current configuration? How much resources are these apps consuming?

–
Aníbal Rojas

http//rubycorner.com

On Mar 1, 6:06 am, John G. [email protected]

7

On Mar 1, 2008, at 2:06 AM, John G. wrote:

that
AMD 64 chip [heard they’re good for lower power + speed]

O/S:
Fedora 8 [works well with AMD cpu’s low-power state]

HDD:
2x SATA2 WD Drives [500gb each, in a RAID 1 config]

Just a side note.

When you setup the machine… I’d highly recommend setting up
separate XEN instances. We do this for a lot of our Managed Hosting
customers at Planet Argon.

Basically, we install the base OS (Linux… usually Debian) with XEN
and then isolate the various pieces of the application for future
scaling needs.

1 - Web server that balances to the app servers
1 - Database server (+1 if you have resources to setup a replication
db xen instance)
2-3 - App servers (nginx + mongrel clusters)
1 - Asset server (memcached, images, etc…)

This ends up working nicely and is a good starting point for future
scaling needs.

Robby

–
Robby R.
Founder and Executive Director

PLANET ARGON, LLC
Design, Development, and Hosting with Ruby on Rails

http://www.robbyonrails.com/
aim: planetargon

+1 503 445 2457
+1 877 55 ARGON [toll free]
+1 815 642 4068 [fax]

8

one thing…

any ideas how to judge power consumption for memory sticks and how much
power a motherboard will consume?

can’t find any technical data on the corsair memory sites anywhere, and
not sure how to judge power requirements for the board.

?

9

Yes, Robby is right on this one too.
I was going to comment about Xen also, but I thought I’d let you
get the hardware part right first.

Not sure about memory consumtion on specific chips or anything…
the best thing to do is to contect your vendor and let them do the
homework.
Its not going to cost any extra and it’ll save you the time!

10

Basically the colocation place i’ve selected for the device has a limit
of 0.5 Amps of power per box, so need to keep the power down below that
limit otherwise it’ll cost more to host.

…
Any ideas how to do the power calculations greatfully received,

0.5A seriously? Yikes that is not a lot of power for a server, that’s
only 120 Watts (240 V * 0.5A = 120 watts).

The low end server you’ve specified (AMD CPU, 4 sticks of RAM, standard
motherboard etc) is easily going to draw 120 W when idle, at load its
going to be more like 300. A modern AMD CPU will be 80W on its own, then
the 1GB of RAM is 10 W (40W), the motherboard is often 40-60W, hard
drives are roughly 20W, you are massively over your power budget even
with this basic machine setup.

I can think of 2 configurations that might get within 120W peak usage:

  1. Use laptop components, ie ultra low usage CPU and memory + reduced
    capability motherbiard and a couple of 4200 rpm hard drives.

  2. Use an embedded chip such as the VIA C7 which you should be able to
    get with a max power draw of around 20 W, combined with their
    motherboard and 2GB of RAM you should again be able to spec something
    below.

Either way you are not going to be looking at a server class machine,
for a reasonable server you are realistically looking at needing 1.5 -
2.0 Amps per machine, which will get you a dual core, 4GB of RAM and 2 x
hard drives basic setup. If possible find another colo - because it
sounds like they have serious power problems.

11

Well I spoke to some experts and they believe that the theory and
practice are totally different. A dell 860 server default spec will pull
about 0.6A, despite being rated at 345 Watts on the PSU. So its average
usage is far lower than you would expect based on the peak figures.

What I also learnt however is that every 0.1 A costs you about £4, so if
you max out your server day and night then you could be looking at £60
extra in power bills on top of your £34 hosting, ouch!

Good luck with your colo, personally based on what I’ve seen I’d be
tempted to go managed unless it really matters, as colocation is looking
like a really expensive option. Do a comparison for instance to Amazon’s
EC2 and its night and day in price. I hope that helps.

12

I have looked further into this and it does appear that many of the UKs
top colocators have similar deals with only 0.5A per 1U. Its a
ridiculously low amount of power for any modern server, because I can’t
find a single one (despite how slow you go) that gets remotely that low.
About the best I can find is a 1Ghz Pentium 3 with 512MB of RAM on Scan
(£350!) that manages to go as low as 240watts. That is still double the
power usage your targeting and its a zillion years old.

I do remember when I was last putting in boxes into a rack at Telecity
(Docklands London) that we couldn’t fill every slot because of power
constraints, and I think we got a maximum of 32Amps for 32U cabinet
there. That is double what most colocators are offering and still half
of what realistically is needed.

I know a lot of data centres don’t like blades as the power density is
high and from IBM you can get 14 blades (that’s upto 28 CPUs, 56 cores
with an E series) in 7U. The power usage as far as I can tell is a
modest 2000 W (8.3 Amps). That is just under 1.2 Amps per blade, which
is closer than most of the 1U servers but still far in excess of fitting
into 0.5A.

There is something I’m missing here because whatever way I look at it I
can’t see 0.5A being remotely doable. I’ve asked some questions of some
colleges who do this sort of thing more often, will get back to you in a
day or so.

13

Thanks Paul for looking into this, seriously appreciate the time and
effort you’re putting in really.

Yep, I had a playaround with Amazon EC2 and found that the service was
good but it proved to be slow in data transfer, was cheap mind.

I’ve sourced parts this weekend and today and still see this as a doable
thing, a friend of mine is doing the same and has managed to put
together a pretty decent AMD 2.4ghz x64 dual core while still keeping
under the limit, hence my attempt.

However it’s more-so out of experience and wanting to try something new,
I’ve never done this and have always viewed it as a grey area in my
experience; i’ve built everything else and run several managed servers
but never tried to build my own.

I’ll let you know how it turns out, waiting on parts to arrive before I
buy the main hardware so it’ll be another month till I really go into
this.

Also thankyou Robby, I want to use XEN to split up the box and will
probably go this route as it adds to the experience gained and your
layout certainly sounds like the way to go; much appreciated.

All the best and thanks for your effort Paul, Robby, Anibal and Ben,
appreciated!

John.

14

You could try a Sun T1000,
6core 1Ghz, 4 x 1Gb ram, 1 x 3.5" sata
SUN power calculator claims 136watts idle 177watts max

OR Sun T5120 (which appears to be over your requirement)
4core 1.2Ghz, 4 x 1Gb ram 2 x 2.5" 73Gb SAS
SUN power calculator claims 159watts idle 232watts max

Aaron

----- Original Message -----
From: “Paul K.” [email protected]
To: [email protected]
Sent: Tuesday, March 4, 2008 7:48:17 AM (GMT+1000) Australia/Sydney
Subject: [Rails-deploy] Re: Building 1U Rails Server - Power
Calculations?

I have looked further into this and it does appear that many of the UKs
top colocators have similar deals with only 0.5A per 1U. Its a
ridiculously low amount of power for any modern server, because I can’t
find a single one (despite how slow you go) that gets remotely that low.
About the best I can find is a 1Ghz Pentium 3 with 512MB of RAM on Scan
(£350!) that manages to go as low as 240watts. That is still double the
power usage your targeting and its a zillion years old.

I do remember when I was last putting in boxes into a rack at Telecity
(Docklands London) that we couldn’t fill every slot because of power
constraints, and I think we got a maximum of 32Amps for 32U cabinet
there. That is double what most colocators are offering and still half
of what realistically is needed.

I know a lot of data centres don’t like blades as the power density is
high and from IBM you can get 14 blades (that’s upto 28 CPUs, 56 cores
with an E series) in 7U. The power usage as far as I can tell is a
modest 2000 W (8.3 Amps). That is just under 1.2 Amps per blade, which
is closer than most of the 1U servers but still far in excess of fitting
into 0.5A.

There is something I’m missing here because whatever way I look at it I
can’t see 0.5A being remotely doable. I’ve asked some questions of some
colleges who do this sort of thing more often, will get back to you in a
day or so.

Posted via http://www.ruby-forum.com/.

15

built it in the end, was a little traumatic but running fine now on 0.4A
in colocation.

ASUS M2A-VM VGA board
WESTERN DIGITAL 1TB green drives x2
CORSAIR XMS2 DDR2 2GB PC2-6400 x2
Dynatron A48G fan (hardest to obtain, get it from ebay)
SuperMicro 1U case (turned off two of the fans so only two blast against
the drives

o/s : debian etch

on the bios remember to turn off things you’ll never use (printer port,
serial port, etc.) to conserve even more power

debians very stable, if you need anything newer just hook it up to the
backports repository.

here’s the commands i ran to deal with the o/s

…i’ll pretty up that later,

hope this helps, let me know if anyone needs any more help on this,

John.