Hyper-V Quick Migration Part III - Downtime no big deal?
4/28/2008 -- Comments

Jeff from the Microsoft Virtualization team posted part III in his continuing series comparing Quick Migration and VMotion. This entry covers planned outages. His point is that most customers plan for downtime anyway, so having some downtime is fine. He also says that in their conversations with existing VMware customers, they still do their maintenance in downtime windows, even though they have VMotion.

I think this is a fair point, but I also think that customers are wanting to get rid of their downtime windows or shrink them. Quick migration helps to shrink it, and VMotion lets you have only uptime - if you want it.

Todd -- Comments




Microsoft VHD Library
4/22/2008 -- Comments

Microsoft has really demonstrated a strong commitment to virtualization in a variety of ways in the last year. I believe that they are putting forth a very strong effort with Hyper-V which will might be the most compelling feature of Windows Server 2008. In addition to this they have begun to provide preconfigured VMs for development, testing, and evaluation for their server products. Their VHD library has grown to include over 15 products including including SQL Server 2008, Visual Studio 2005, Windows Server 2008, and Vista.

SQLBLog.com has a related post on how to overcome some minor issues that sometimes pop up with these VMs, like the mouse disappearing. As virtualization becomes more mainstream, there will be minor problems like these that pop up from time to time. The time savings with being able to very quickly setup a VM to evaluate new software - is worth it.

Todd -- Comments




Hyper-V Quick Migration Part II
4/18/2008 -- Comments

The second post on the Microsoft Virtualzation Team Blog about Quick Migration and VMotion was added a few days ago. It is mostly a discussion about how VMware HA and Quick Migration both provide a failover solution for UNplanned downtime. I agree with Jeff that both do basically the same thing in the event of an unplanned server outage - the VM is moved to another server and restarted.

The difference that he doesn't talk about is that the rules of the failover are different because of the underlying filesystem that is used in each solution. Microsoft Hyper-V and Quick Migration are using the tried and true Microsoft failover-clustering, which uses an NTFS filesystem on the shared storage. As this is not a cluster file system, the shared storage is actually only visible to one of the servers at a time to prevent corruption. VMware ESX server and VMware HA are working with VMs that are on a VMFS file system which is cluster aware - meaning that multiple ESX servers are able to access the files (or VMs in other words) at the same time.

So following a failure of a Hyper-V server, all VMs on the same disk (or LUN) must be recovered on the same server because the LUN or disk can only be used by one server at a time. In the event of a failure of an ESX server, the VMs can be restarted on any ESX server that has access to the LUN. In order to achieve this flexibility with Hyper-V and Quick Migration it would be necessary to have each VM on it's own LUN. This isn't impossible, but could be more complex to setup and manage.

The end result would be same - the VMs would be restarted on another server. Some of the underlying details can make a difference with flexibility in where those VMs end up.

Todd -- Comments





Virtual NIC Performance
4/17/2008 -- Comments

During our regular TechTuesday webchat, a question came up about virtual NIC performance. The topic this week was Running Enterprise Apps on VMware, and one aspect of that is performance. Hywel, who has a successful SQL Server deployment on ESX, asked - why is he only getting 250 mb/s of throughput? I found a VMware blog post and a whitepaper that indicate it is possible to get much higher. Of course in real-world use through-put will be lower, but I would think that you could top 250 mb/s. I believe that the key to getting the best performance form a virtual NIC in VMware is to install the VMtools and use the VMxnet NIC.

Todd -- Comments




A ScreenShot for Geeks
4/14/2008 -- Comments

I will be the first to admit that I haven't always been a fan of using the biggest baddest system you can find for ESX servers, but some things have changed and I do realize there are cases where really big systems make sense. Which brings me around to the newest system that we ordered for the lab - an R900 with four quad-core top bin processors and 128GB of RAM. This arrived in the lab on Thursday morning and I had ESX on it late that afternoon.

When I saw the system in Virtual Center, it really hit home just how much power you can get in a single system these days. This screen shot is something that only a geek would love (16 CPUs and 128GB of RAM!).



I'm thinking of doing some Exchange 2007 testing.... If I can just find enough disks.

Todd -- Comments




Hyper-V Quick Migration Part 1
4/10/2008 -- Comments

Jeff from the Microsoft Windows Server Virtualization team posted yesterday on their team blog the first in a promised 4 part series on Hyper-V HA and Quick Migration and it's differences with VMware's VMotion or live migration. This first post doesn't really get into the differences, but does a good job of explaining why you need an HA for a virtualizaiton solution.

I am really looking forward the other posts to get the full rundown on quick migration. Jeff makes a reference that this series of posts is in response to "buzz" on the internet. I can only guess that part of that buzz is due to things like a recent video posted by David Marshall on vmblog.com showing Hyper-V Quick Migration in action, and discussions in a few places including the RTFM Education blog, blog.scottlowe.org, and the From the VMware Field Blog.

So it will be good to get Microsoft's side of the story.

Todd - Comments




Is it Cool to Use Virtualization?
4/9/2008 -- Comments

These days, it seems like everybody is at least looking at using VMware or Xen or some other virtualization solution. It's the cool thing to do. Clearly.

But what about when you run something like Exchange or SQL Server or Oracle? It seems that almost everybody is cool with virtualization, until you start talking about stuff like this. Then there is a pause. Some decide to push forward, others decide to wait, still others may declare that they would never do it!

There are lots of issues to consider including support, performance, backup, disaster recovery, and even non-technical things like organizational structure and management support. So the answer for everybody isn't the same. The next TechTuesday chat is going to have this as it's discussion point - Running enterprise apps virtualized - to let everybody learn from each other.

Todd - Comments





SQL Server on VMware Server
4/4/2008 -- Comments

I recently ran across this blog entry on Scott's Blog (no relation to Scott Hanson on my team) about a migration of a SQL Server DB to a VM running VMware Server. I have spent only limited time working the the VMware Server (formerly GSX) product and instead have concentrated on ESX. This entry has some interesting info about their experiences with getting SQL Server production DB performing at acceptable levels including a nice "lessons learned" section at the end. For those thinking about going the VMware Server route, then this is a great read.

Todd -- Comments





Running SQL Server in a VM
4/2/2008 -- Comments

I published a new white paper this week on running SQL Server in a VM. The paper focuses on the performance of a large (well 100 GB) version of the DVD Store when running on 64-bit SQL Server 2005. I started this testing just after ESX Server 3.5 was finished and made available, and I believe that it is the first paper with performance numbers of SQL on ESX 3.5 (Please correct me if there are some!). In addition to the paper we had a web chat on Tues on the topic. And I have setup a wiki page to collect SQL on VMware resources and serve as a central place to host threads.

A couple of interesting notes, well at least interesting in a kind of really geeky way:

The first performance study on VMware that Dell published was a paper by Dave Jaffe and I on VMotion performance. We used a 1 GB version of the DVD Store database on SQL Server 2000 as the test VM. So this test really is an update in some ways to that paper. Same basic conclusion regarding VMotion with SQL Server - it is very hard to measure or detect the impact to DB performance of a VMotion.

This study was similar in many ways to the testing that Kong Yang and I did late last year on Exchange 2007. Key difference is that SQL Server is much easier to test! Exchange and LoadGen have extremely time consuming requirements to setup and initialize testing, but the DVD Store on SQL Server can be created and loaded in a much shorter time, and includes cleanup or resetting scripts that are also very fast.

Todd -- Comments