[mdlug] linux hardware

[Michael ORourke]

Well I can't believe I'm saying this, but for once, I agree with Aaron.  ;-)
I'm not sure about the math on the page faults, but having enough memory to 
keep your system happy will pay off in performance down the road.

On that budget, you are not talking about server class hardware, SCSI/SATA 
hardware RAID, redundant power supplies, etc...  Realistically you are 
looking at a desktop-class machine masquerading as a server.  Don't get me 
wrong, I'm not against doing that.  In fact I've built several "servers" 
using that exact approach.  I see it as a win-win, because the client gets a 
stable "server" but without all the hardware expense and proprietary OS tax.

That being said, I would highly recommend getting 2 drives and setup RAID 1 
(mirroring).  While you are at it, why not throw in a 3rd drive for backups. 
Virtualization may or may not be necessary, depending on your needs.  On a 
lower powered "server", I would probably stay away from virtualization.

-Mike


----- Original Message ----- 
From: "Aaron Kulkis" <akulkis00 at gmail.com>
To: "MDLUG's Main discussion list" <mdlug at mdlug.org>
Sent: Friday, December 04, 2009 7:26 PM
Subject: Re: [mdlug] linux hardware


> epic wamz wrote:
>> I've been asked by a friend who is running a small business to help him 
>> purchase and setup a linux server. I'm kind of known as a linux 
>> evangelist, so it makes sense why he asked me, but I don't know much 
>> about purchasing server hardware, and frankly I haven't built a computer 
>> from the ground up in a good 6-7 years.
>>
>> So, I thought I would drop a quick message to see if someone could give 
>> me any advice. I'm not asking for you to do the research for me, but a 
>> gentle nudge in a good direction would be appreciated.
>>
>> My friend wasn't specific about the server capabilities he needs. He has 
>> a growing technology business and wants to be as agile as possible. 
>> Sounds like it could be used as a web server, subversion repo, and used 
>> for virtualization among other things. I'm not really looking to build 
>> from scratch, so any advice on where to go, or tips when buying a system 
>> would be most welcome.
>>
>> The budget is $500 +/- $100.
>
> #1: Buy AMD... you'll always get better performance/$.
>
> #2. For fast (wall-clock time) execution, you want to put your
>    money in memory.
>
> Given equal budgets where you can NOT have both the highest speed
> CPU and 8GB of memory, and running a busy computer that's doing
> lots of things, if you spend most of your money on the fastest
> CPU available and whatever is leftover on memory, and I spend
> money first on memory, and then buy the cheapest 64-bit CPU
> available, and all else is equal, my machine will beat your
> machine every day.
>
> Why?  Because it doesn't matter how fast your CPU goes when your
> system is swapping memory.  Page faults are expensive -- with
> modern CPUs, you're talking about 500,000,000+ clock cycles lost
> whenver a page fault has to be serviced from a hard drive (Due
> to the CPU not being able to do ANYTHING towards completing the
> program during this time).  And this happens EVERY time a
> page fault occurs.  More memory => fewer page faults =>
> faster system responsiveness.
>
>
>
>
>
> #3: Virtualization on < $600?
>
> Not happening.  Unless you're talking about EXTREMELY small
> footprints for the virtualized hosts. And slower than molasses
> in February. Because now you have to keep MULTIPLE operating
> systems in memory, or suffer HUGE performance problems.
> (See memory (#2), and then make the cost of page faults
> more expensive than linear (thing  k * N log N, or possibly
> even k*N*N, where N is your page faults/minute).
>
> 4GB of memory is going to cost you about $80.
> For virtualization, you're going to want 8GB...but if you do it
> on an economical motherboard that doesn't have 8 memory slots,
> you're going to have to buy 2 GB sticks, and that will run
> you over $200 for the memory.
>
> Not to mention a quad-core for decent virtualization performance.
> That's another $200.  Now you only have $200 left for your
> motherboard, and other assorted things. You'll have to
> spend AT LEAST $100 for a motherboard that will take
> 8 GB of memory.
>
>
>
> In most cases, the inherent multi-programming of Linux
> beats virtualization. (that is, run the fileserver, and
> webserver under the same OS, WITHOUT virtualization,
> rather than running two virtualized servers).
> Without virtualization, you can easily do that within
> your budget.
>
>>
>> Again, I would appreciate any insight you might have. Thank you in 
>> advance.
>>
>
> Your best bet is to find out EXACTLY what he wants the system
> to do, and then proceed from there.
>
> Note: Unlike Windows, it is not, and never has been, unusual
> for a Unix or Linux machine to be set up to perform MULTIPLE
> services (printing, mail, file serving, etc.) with ZERO
> increase in instability (whereas I understand that in the
> land of Microsoft, it's typically the other way around --
> two or three computers devoted to nothing more than printing,
> another group for file serving, and still another group
> for mail serving.  This is a wasteful underutilization of
> hardware.  I think MS has avoided solving stability problems,
> because if the "solution" is to throw multiple hosts at
> even trivial problems, they can sell TEN copies of Windows
> to do the same amount of work as one Linux machine -- I
> have never seen any other company (except for those in the
> recording industry) which is so blatantly hostile to their
> own customers.
>
>
>> Ryan
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