Quad Opteron Style Dell

Offering an interesting platform is one thing. The next challenge is to have an OEM partner that makes the right trade-offs between scalability, expandability, power efficiency and rack space. And that is where the DELL R815 makes a few heads turn: the Dell R815 is a 2U server just like the dual Xeon servers. So you get almost twice the amount of DIMM slots (32) and twice the amount of theoretical performance in the same rack space. Dell also limited the R815 to four 115W Opteron 6100 CPUs (quad 137W TDP Opteron SE is not possible). This trade-off should lower the demands on the fans and the PSU, thus benefiting the power efficiency of this server.

Compared to its most important rival, the HP DL585, it has fewer DIMM slots (32 vs. 48) and PCIe slots. But it is again a balanced trade-off: the HP DL585 is twice as large (4U) and quite a bit pricier. An HP DL585 is 30 to 40% more expensive depending on the specific model. HP positions the quad opteron DL585 right in the middle between the HP DL380 G7 (Dual Xeon 5600) and the HP DL580 (Quad Xeon 7500). The HP DL585 seems to be targeted to the people who need a very scalable and expandable server but are not willing to pay the much higher price that comes with the RAS focused Xeon 7500 platform.

Dell’s R815 is more in line with the “shattering the 4P tax” strategy: it really is a slightly more expensive, more scalable alternative to the Dual Xeon 5600 servers. Admittedly, that analysis is based on the paper specs. But if the performance is right and the power consumption is not too high, the Dell R815 may appeal to a lot of people that have not considered a quad socket machine before.

Most HPC people care little about RAS as a node more or less in a large HPC cluster does not matter. Performance, rack space and power efficiency are the concerns, in that order of importance. The HPC crowd typically goes for 1U or 2U dual socket servers. But in search for the highest performance per dollar, twice the amount of processing power for a 30% higher price must look extremely attractive. So these dual socket buyers might consider the quad socket R815 anyway.


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As a building block for a virtualized datacenter, the R815 makes a good impression on paper too: virtualized servers are mostly RAM limited. So if you do not want to pay the huge premium for 16GB DIMMs or Quad Xeon 7500 servers with their high DIMM slot counts, the R815 must look tempting.

In short, the quad Opteron 6100 Dell R815 could persuade a lot of people on two conditions. The first one is that the two extra CPUs really offer a tangible performance advantage, and that this happens with a minor power increase. So can the Dell R815 offer a superior performance/watt ratio compared to the dual Xeon 5600 competition? Well, that is what this article will try to find out. Let us take a closer look at the benchmarked configurations of the three competitors: the Dell PowerEdge R815, the HP Proliant DL380 G7 (dual Xeon X5670) and the QSCC-4R / SGI Altix UV10.

The Quad Opteron Alternative Dell R815: Benchmarked Config
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  • JohanAnandtech - Friday, September 10, 2010 - link

    Thanks, appreciate you took the time to let us know. We went through 5 weeks of intensive testing and my eyes still hurt from looking at the countless excel sheets, with endless power and response time readings. ;-) Reply
  • FourthLiver - Thursday, September 09, 2010 - link

    at the end of page 12, you allude to a performance per watt analysis. looks like you forgot to put it up. i'm chomping at the bit to see those numbers!

    please disregard me if i failed to rtfa correctly. Anandtech is the best; your (all of you collectively) articles are brilliant and correct down to the smallest details. This is another article that was an absolute joy to read. :]
    Reply
  • JohanAnandtech - Thursday, September 09, 2010 - link

    Well you can't really calculate it, as it depends on the situation. On low load loads, the system that consumes the less, is the winner, on the condition that the response times stay low. But of course, if your systems are running at low load all time, there might be something wrong: you should have bought more RAM and consolidated more VMs per system.

    At higher loads, the power consumption at high load divided by the throughput (vApusmark) is close to the truth. But it is definitely not the performance/watt number for everyone

    It depends on your workloads. The more critical processing power (think response time SLA) is, the more the last mentioned calculation makes sense. The more we are talking about lots of lightly loaded VMs (like authentification servers, fileservers etc.), the more simply looking at the energy consumed at page 12 make sense.
    Reply
  • mino - Thursday, September 09, 2010 - link

    First, congratulations to a great article !

    Now to the small ammount of mess in there:
    "the CPUs consume more than the ACP ratings that AMD mentions everywhere"

    1) Avegare CPU Power (ACP) is NOT supposed/marketed to represent 100% load power use
    Wikipedia: "The average CPU power (ACP), is a scheme to characterize power consumption of new central processing units under "average" daily usage..."

    2) 122W at the wall and 110W at the CPU ??? Are you telling us the PSU's are 95% along with VRM/power/fans at 95% efficiency ? (0.95*0.95*1.22=1.10)
    . Sorry to spoil the party but that is NOT the case. 122W at wall means 100W at CPU at the most realistically 95W.

    Otherwise a great work. Keep is up!
    Reply
  • JohanAnandtech - Friday, September 10, 2010 - link

    "1) Avegare CPU Power (ACP) is NOT supposed/marketed to represent 100% load power use
    Wikipedia: "The average CPU power (ACP), is a scheme to characterize power consumption of new central processing units under "average" daily usage...""

    You are right. But what value does it have? As an admin I want to know what the maximum could be realistically (TDP is the absolute maximum for non-micro periods) and if you read between the lines that is more or less what AMD communicated (see their white paper). if it is purely "average", it has no meaning, because average power can be a quite a bit lower as some servers will run at 30% on average, others at 60%.

    These PSU are supposed to be 92-94% efficient and AFAIK the VRMs are at least 90% efficient. So 122 x 0.92 x 0.90 = 101 W.
    Reply
  • mino - Saturday, September 11, 2010 - link

    Well, I was bit unslept when writing it but anyway. So got a bit harser than should have.

    In my experience the ACP values pretty well represent your average loaded server (<= 80% load). But that is not the point.

    AMD created ACP in a response to the fact that their TDP numbers are conservative while Intel's are optimistic. That was the main cause wery well known to you as well.

    Call me an ass but I certainly do not remember AT bitching about Intel TDPs no bein representative (during last 6 years at least).
    And we all know too well that those NEVER represented the real power use of their boxen nor did they EVER represented what the "TDP" moniker stands for.

    Currently the situation is as such that identical 2P AMD box with 80W ACP has ~ the same power requirements as 2P Intel box with 80W TDP. You have just proven that.

    Therefore I believe it would be fair to stop bitching about AMD (or Intel) cheating in marketing (both do) and just say whether the numbers are comparable or not.
    Arguing about spin wattage is not really needed.
    Reply
  • JohanAnandtech - Monday, September 13, 2010 - link

    "Arguing about spin wattage is not really needed. "

    I have to disagree. The usual slogan is "don't look at TDP, look at measurements". What measurments? The totally unrealistic SPECpower numbers?

    It is impossible for review sites to test all CPUs. So it is up to vendors to gives us a number that does not have to be accurate on a few percent, but that let us select CPUs quickly.

    Customers should have one number that allows them to calculate worst case numbers which are realistic (heavily load webserver for example, not a thermal virus). So all CPU vendors should agree on a standard. That is not bitching, but is a real need of the sysadmins out there.
    Reply
  • mino - Thursday, September 09, 2010 - link

    One thing I would love to see is having the lowest end HP server put to its paces.
    So far it seems to us a the best option for vCenter hosting in small environments (with FT Vm's hosting vCenter).

    Maybe even run 1-tile vAPUS (v1? perhaps) on it ?
    Reply
  • m3rdpwr - Thursday, September 09, 2010 - link

    I would have prepared to have had the DL385 G7 compared.
    They can be had with 8 and 12 core CPU's.

    We have close to 200 HP servers of all models, rack and blades.
    Many running vm in our Data Center.

    -Mario
    Reply
  • duploxxx - Friday, September 10, 2010 - link

    same here, we moved also to 385g7 with the new 8-12core cpu's, Nice servers with huge core count since we never run more vCPU then pCPU in a system. Dell 815 looks like a good solution also, it was mentioned in the review the BL685 and DL585 are way more expensive. Reply

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