Sizing replacement servers

Sizing replacement servers

Post by Joe D » Fri, 01 Sep 2006 04:15:14


Hello all; I have a question regarding replacing older Sun servers,
particularly regarding CPU horsepower.

Here's a for instance: We have a couple of 420R servers, with 4 GB Ram
and 4 X 450MHz CPUs. In spec-ing replacements, I'm looking at V440
servers. Since RAM is (relatively) cheap, I'm gonna spec the same
amount of RAM, but CPUs are a different story. I can simply spec them
with 4 CPUs, but on this model, the CPUs range from 1 GHz to 1.5 GHz.
Plus, the price jump from 2 to 4 CPUs is about 10 grand (list, of
course).

Can I simply say "well, 4 X 450 GHz is 1800 GHz, so I'll spec them with
2 X 1.5 GHz CPUs for a total of 3 GHz of CPU power, and we'll be set
for the current load, and have room for growth before we have to add
processors"?

I know, I know, I should have some stats gathered to gauge how well our
4 CPUs are doing for us now, but this was sprung on me last minute, and
I need to get rough numbers to management ASAP.

Any assistance, rules of thumb, or other advice gratefully
acknowledged, as always.

Joe D.
 
 
 

Sizing replacement servers

Post by Michael Vi » Fri, 01 Sep 2006 04:41:22

In article < XXXX@XXXXX.COM >,



Well, you could do "first blush" estimates giving as much time to it as
the PHB who asked for it did. If you know what the budget is, get as
much hardware as you can.

Or quote the full memory and all 4 1.5GHz CPUs.
In another, price full memory and 4 1GHz CPUs.
In another, price full memory and 4 1.5GHz CPUs.

Bet they go for the cheapest. If you think that will be the case, don't
quote anything less than 4 CPUs until you know your workload doesn't
need all of them. So what if they're faster. IMO, workloads don't
scale the way you're thinking. Unless you have reviewed your sar and
mpstat statistics and know that you're underutilizing the 4 CPUs, you'll
probably miss them if you don't have them. You know your workload best.

Work the system to get as much machine as you can. Maybe this is just a
chinese firedrill and the PTB (powers that be) look at how much and tell
you "Never mind".

--
DeeDee, don't press that button! DeeDee! NO! Dee...

 
 
 

Sizing replacement servers

Post by tunl » Fri, 01 Sep 2006 06:25:45


Today you need to look at the workload first of all.

if the workload is transaction based in many threads go for the
T1000/T2000 servers.
If the workload is more HPC simulation with few threads get the
fastest CPU's
available. If you S/W is SPARC based that would be the new US-IV+
CPU's and
the E2900 chassie. or possible the V440 with the 1.59 GHz CPU or
the Ultra 45 workstation
with the same CPU.


To run a web/Apllication server / medium database on anything else
than a T1000/T2000
today is daft, and a waste of time and money.


//Lars
 
 
 

Sizing replacement servers

Post by Richard B. » Fri, 01 Sep 2006 08:45:09


4 X CPUS does not compare well with N CPUS of different power. If there
are not N schedulable processes (or threads), you can't use all N CPUs.

I'd say your best bet is to tell management that they can have it done
right or they can have it Tuesday. If you don't have a good picture of
your workload and how your machines handle it, any recommendation you
make stands a good chance of being useless (or worse).

How much swapping are the current machines doing? If it's significant,
get more memory. Are you actually keeping 4 CPUs busy? If not, it's a
waste of money to configure four. If you are, you may want to think
more or faster or both.

Buying a new server is usually a substantial investment. Getting it
right is, therefore, usually worth the time and effort.
 
 
 

Sizing replacement servers

Post by Chris Lawr » Fri, 01 Sep 2006 09:35:52


Can you name the applications running on each server at the moment, or
detail the business functions of each server? Also why are you
replacing the servers?

--
Chris
 
 
 

Sizing replacement servers

Post by Joe D » Thu, 07 Sep 2006 04:13:27


Yes, I can; however, we are merely at the "let's see if we can get
money allocated" stage right now. As several previous replies had
pointed out (and I think your question was leading to as well), I will
need to spend some time actually monitoring the load on each server
before spec'ing something. So it's more of a spin the wheels exercise.

One thing of note was a comment one of our VARs mentioned when I asked
about sizing today's CPUs vs. yesterday's. Apparently, there is some
sort of service that SUN provides that will allow you to calculate an
'm-value' (I may have mis-heard him) for processors, whereby they can
tell you, all things being equal, the number and speed of processors
needed to replace an existing configuration of X number of Y speed
CPUs.

I suspect that this would be a very subjective thing, and not
reflective at all of some of the points made earlier (curent CPU load,
type and amount of work being done, etc.). Has anyone heard of this
'service', or is this smoke and mirrors by Sun Services to drum up more
business?

Anyay; thanks as usuall to all who responded. As usual, I have gleaned
more from this group than I am contributing, an imbalance I am hoping
to rectify, just as soon as I see a posting that I can actually
contribute something of worth to! : )
 
 
 

Sizing replacement servers

Post by Richard B. » Thu, 07 Sep 2006 04:50:23


Any, ANY, such thing has a large component of subjectiveness and
guesswork. The only certain way to determine how your applications
would perform on a given system is to benchmark them on that system.
Sometimes that's easy to do. Sometimes a realistic benchmark would
require installing 200 users and a quarter of a terrabyte of database
and it's anything but easy. Having said that, sometimes an expert can
make a very good guess; especially if said expert has no financial
interest in the outcome.
 
 
 

Sizing replacement servers

Post by Josh McKe » Thu, 07 Sep 2006 08:24:53

In article < XXXX@XXXXX.COM >,





Recall the wise words of Brian Wong:

"You can never say with certainty that a given configuration will be
able to meet your needs. You can only be certain that a given
configuration cannot meet your needs."

Paraphrased of course.

Josh