Virtualization Frontier

Wiggle Room in Deciding on a Virtualization Server

ToddMuirhead — Sat, 07 Jun 2008 15:33:00 GMT

What is the best server for virtualization? This is a question that comes up often in discussions, although it is sometimes phrased differently. It might be "How many NICs do you recommend for ESX?" or "How much RAM can you put in an R805?" or "Are blades the most power efficient server?". The really cool thing is that the answer to all of them ends up being the same - If you can tell me what you are trying to do, and the key requirements that you have, I can give you the best answer. Sometimes you need tons of RAM, sometimes you oodles of NICs, and sometimes you are looking for the best value.

We can give you some basic guidance and even provide you with reference architectures, but ultimately everybody has to customize their virtualization solution based on their needs. To provide you with the ability to be able to customize, you have to be educated about what your choices are what the ramifications are for each choice. That's what this focus topic on Selecting a Virtualiation Server has been all about. Connecting people with the information as well as each other for discussion about the process. This played out in each of the three chats that we did, and can continue on the discussion threads.

This really isn't anything new in the IT world. Almost all solutions have required a certain amount of planning and sizing that was specific for each organization. The advantage with virtualization is that there is more wiggle room to adapt and learn as you go. Because virtualization provides a layer between the VMs and the physical servers, things can be changed, modified, tuned much more easily than without virtualizaiton. If you find that a server is overloaded with too many VMs, you can use VMotion to move some to another server. If you find that you are out of capacity, you can add another server to the farm and redistribute the VMs to take advantage of the new capacity - without any downtime.

Use this community to keep the discussion going about what the best server is for virtualization - all questions around this topic are welcome. The opportunity to interact with your peers and find out why and how they made their decisions is really the best answer to a question that has a different answer for everybody.

Todd

Iniside IT Video is Still True

ToddMuirhead — Mon, 02 Jun 2008 19:15:00 GMT

I didn't get a chance last week to draw attention to the nice video that Marc Farley put up on the InsideIT blog last week about our TechCenter web chats. Marc is a regular attendee of our weekly chat sessions and he is also the lead blogger on InsideIT. The video is cool, short, and just as relevant this week as last. This week's chat (Tues 3 PM CST) will be about when to select blades for your virtualization server platform.

Todd

Oodles of NICs for ESX

ToddMuirhead — Mon, 02 Jun 2008 19:10:00 GMT

Back in the ESX 2.5 days it was a common recommendation to have at least 3 NICs for ESX. One NIC each for the service console, VMotion, and VMs. It was really a waste for many to have to dedicate an entire NIC for the low network traffic to the service console. Then with ESX 3 the networking features became more flexible, and you could easily setup the service console to share a NIC with VMotion or the VMs.

The M600 and M605 blades for the Dell M1000e blades chassis now have two on-board NICs and the option to add two more I/O cards, each with two ports of either Ethernet or fibre channel. This means that you can have four NICs and two fibre channel ports for storage OR six NICs with 2 dedicated to iSCSI for storage. The four available NICs for VM data traffic is usually enough, although I admit there are always exceptions.

So if the I/O options on the blades are not enough there are options with the R805 and R900 and R905 that offer oodles of NICs. Specifically the R805 has four on-board NICs and four PCI slots. Filling these slots with your required mix of quad-port NICs and dual-port fibre channel HBAs would be a great solution for environments that have high requirements of physical NICs to support their VMware environment.

Todd

Ultimate Power Efficiency with Blades and Virtualization?

ToddMuirhead — Thu, 29 May 2008 20:31:00 GMT

A recent thread here on delltechcenter asked for a power consumption comparison between the PowerEdge 1950 1U rack mount server vs the PowerEdge M600 blade. It turns out that there are a few whitepapers that have been done on 2950 power consumption and a big study on the blades power consumption - but nothing I can find that directly compares the two. The best way to get a comparison between just about any current or recent Dell server is to use the Dell Datacenter Capacity planner. It allows you to build out a rack of servers and get an estimate of power consumption.

If you use similar configurations for 16 PowerEdge 1950s and a full M1000e chassis (16 blades) then the blades configuration will consume less power. So you can save a significant amount of power by going with blades over similar traditional rack mount servers.

If you combine the efficiencies of the blades with the efficiencies of running lots of VMs on a single physical server - you might have the ultimate in power efficiency. This is one reason to use blades for virtualization - we'll be chatting about this and other reasons next week in our TechTuesday chat.

Todd

VMotion Compatibility and Server Selection

ToddMuirhead — Thu, 22 May 2008 15:12:00 GMT

On the TechTuesday chat yesterday the topic was Selecting a Server for Virtualization, and we had an excellent discussion. One of the points that came up was the importance of understanding VMotion compatibility between different servers. On easy rule is that it is not possible to VMotion between AMD and Intel processors. As these are completely different processors in many respects it is easy to understand how it is not possible to move a running VM from one to the other with no downtime. The next aspect that VMotion will not work across different generations of processors. The difficulty here is that processor generations do not always line up with Dell server generations. So even if you have all Dell 9G servers, there are cases where VMotion will not work.

It really comes down to the instruction set that each processors is using. A running VM has identified the processor that it is running on and is expecting a certain instruction set to be available. If this were to suddenly change in the middle the OS would not be able to cope or adapt and would most likely crash. There has been some work done to improve the situation - but as of today it is still an issue.

The answer to this problem is the compatibility matrix that our virtualization engineering team has put together and updates as new servers are released. It is important to consider this matrix when selecting a server if VMotion is in use.

Todd

Bumping Into It on VMTN

ToddMuirhead — Tue, 20 May 2008 19:31:00 GMT

I just ran into a thread on VMTN that is exactly what we are hosting a chat on later today. The VMTN thread is titled Physical Hardware Recommendation, but I am calling the same topic Selecting a Virtualization Server. Very coincidental that this thread was started today and it even specifically asks about 2950s and R900s. So for the record - this VMTN thread was not a planted thread by me or some secret Dell conspiracy. I do have to confess that it was Scott that spotted this thread first and he deserves the credit (Again!).

Todd

The Best Server for You

ToddMuirhead — Mon, 19 May 2008 12:20:00 GMT

For the past three weeks, we at the Dell TechCenter have been focused on the decoder ring for systems management. Starting today we are going to tell you what the best server is for virtualization. The reason it is going to take three weeks is that the answer for everybody is different. So we are going to talk about key factors, advantages of one type of server over another, and learn from the decisions and thought processes of each other. We are simply hosting the conversation and I do not have a "favorite server" -- although I must admit that I used to lean heavily towards 2-socket servers.

The decision for most seems to come down to 2-socket, 4-socket, or blades servers. I hope that we end up expanding the conversation and talk about lots of other possibilities including storage options, hypervisor options, and who knows what else.

In order to get things going are going to have some chat sessions, there is a topic home page, and a server selection matrix page to specifically lay out the facts about each type of server. I've started the page off with 2-socket, 4-socket, and blades as server categories with some basic tech specs and advantages for each type. This page will grow as additional pros, cons, and others ideas come up.

Todd

VMmark Results Point to Best Performance

ToddMuirhead — Thu, 15 May 2008 20:25:00 GMT

New VMmark benchmark results highlight that the best performance for a single server is a 4-socket (or 16 cores with Quad-Core processors). This means that the R900 and R905 are at the top of the list, with the Intel based R900 slightly ahead of the AMD based R905. So if you absolutely need the most performance possible from a single server - then this is the way to go.

A little bit of analysis could lead you to believe that the 2-socket (or 8 core) servers are actually better performing. The VMmark score for the 4-socket R900 is 14.23 with 10 tiles, but the VMark score for the 2-socket 2950 III is 8.47 with 6 tiles. So on a per socket basis, the two-socket 2950 III is actually providing more performance. The same holds true for the two-socket M600 blade and two-socket R805 2U server.

There is much more to choosing a server than the results of a single benchmark, but I think that these results are fair barometers of performance. In general performance does not scale in a linear fashion when moving from 2-socket servers to 4-socket servers, and this seems to hold true with virtualization.

Todd