Server Clash: DELL's Quad Opteron DELL R815 vs HP's DL380 G7 and SGI's Altix UV10

vApus Mark II

vApus Mark II is our newest benchmarksuite that tests how well servers cope with virtualizing "heavy duty applications". We explained the benchmark methodology here.

* 2 tiles instead of 4 tiles test
** 128GB instead of 64GB

Before we can even start analyzing these numbers, we must elaborate about some benchmark nuances. We had to test several platforms in two different setups to make sure the comparison was as fair as possible. First, let's look at the Xeon 7560.

The Xeon 7560 has two memory controllers, and each controller has two serial memory interfaces. Each SMI connects to two memory buffers, and each buffer needs two DIMMs. Each CPU needs thus eight DIMMs to achieve maximum bandwidth. So our Quad Xeon X7560 needs 32 DIMMs. Now, we also want to do a performance/watt comparison of these servers. So to accomplish this, we decided to test with 16 DIMMs (64GB) in all servers. With 16 channels, bandwidth goes down from 58GB/s to 38GB/s and bandwidth has a tangible impact in a virtualized environment. Therefore, we tested with both 128GB and 64GB. The 128GB number represents the best performance of the quad Xeon 7560; the 64GB number will allow us to determine performance/watt.

Next the dual Opteron and dual Xeon numbers. We tested with both 2- and 4-tile virtualization scenarios. With 2-tiles we demand 36 virtual CPUs, which is more than enough to stress the dual socket servers. As these dual socket servers will be limited by memory space, we feel that the 2-tile numbers are more representative. By comparing the 2-tile numbers with the 4-tile numbers, we take into account that the quad socket systems will be able to leverage their higher number of DIMM slots. So comparing the 2-tile (Dual Socket) with the 4-tile (quad socket) is closest to the real world. However, if you feel that keeping the load the same is more important we added the 4-tile numbers. Four tile numbers result in slightly higher scores for the dual socket systems, and this is similar to how high VMmark scores are achieved. But if you look at the table below, you’ll see that there is another reason why this is not the best way to benchmark:

The four tiles benchmark achieves higher throughput, but the individual tiles perform very badly. If you remember, our reference scores (100%) are based on the quad-core Xeon 5570 2.93. You can see that the 4-tile benchmark runs achieve only 13% (Opteron) or 11% (Xeon) of a quad Xeon 5500 on the Oracle OLTP test. That means the OLTP VM gets less than a 1.5GHz Xeon 5570 (half a Xeon 5570). In the 2-tile test, the OLTP VM gets the performance of a full Xeon 5570 core (in the case of AMD, probably 1.5 Opteron “Istanbul” cores).

In the real world, getting much more throughput at the expense of the response times of individual applications is acceptable for applications such as underutilized file servers and authentication servers (an active directory server might only see a spike at 9 AM). But vApus always had the objective of measuring the performance of virtualized performance critical applications such as important web services, OLAP, and OLTP databases. So since performance matters, we feel that the individual response time of the VMs is more important than pure throughput. For our further performance analysis we will use the 2-tile numbers of the dual Xeon and dual Opteron.

The quad Xeon has a 15% advantage over the quad Magny-cours. In our last article, we noted that the quad Xeon 7560 might make sense even to the people who don’t feel that RAS is their top priority. The reason was that the performance advantage over the dual socket server was compelling enough to consider buying a few quad Xeons instead of 2/3 times more dual Xeons. However, the Dell R815 and the 48 AMD cores inside block the way downwards for the quad Intel platform. The price/performance of the Opteron platform is extremely attractive: you can almost buy two Dell R815 for the price of a quad Xeon server and you get 85% of the performance.

The performance advantage over the Dual Xeon X5670 is almost 80% for a price premium of about 30%. You need about twice as many dual Intel servers, so this is excellent value. Only power can spoil AMD’s value party. We’ll look into this later in this article.

Although the quad Opteron 6136 may not enjoy the same fame as its twelve-core 6174 sibling, it is worth checking out. A Dell R815 equipped with four 6136 Opterons and 128GB costs about $12000. Compared to the dual Xeon 5670 with 128GB, you save about $1000 and get essentially 40% more performance for free. Not bad at all. But won’t that $1000 dissipate in the heat of extra power? Let us find out!