Do you know how there are some questions that at first glance seem like they may generate long and complicated answers? Recently I was pinged with such a question, but then I came to realize that the my original answer, and in fact the question itself were both over thinking the situation. The question is, “What problems are there with running various virtualization solutions in the same data center?”
The answer is simple — there really are not any problems that do not already exist in any given data center that employs heterogeneous technologies. For example, there are the problems of redundancy, vendor support, free storage space, and staff expertise.
Imagine a data center that runs both Apache and IIS web servers. There are 2 Apache servers and 2 IIS web servers — the Apache servers run PHP applications and the IIS servers run ASP.NET applications. What happens if either all of the Apache servers go down or all of the IIS servers go down. Because all 4 servers do not use the same web server and the web applications are not based on the same language, the odds of quickly and successfully moving the load of the 2 downed servers to the other 2 are slim.
The same goes for a data center that implements various virtualization technologies. For every different technology employed, you potentially lose a little bit of redundancy.
In a given data center imagine there are Dell servers, HP servers, and IBM servers. That means 3 different vendors (unless you went through a VAR) for supporting your infrastructure. The same is true for virtualization software — having multiple virtualization solutions means having different vendors to contact when problems occur.
Free Storage Space
Available storage space is usually scarce in any data center. There is almost always someone or some system clamoring for more spindles. Throwing additional virtualization solutions into a single data center results in additional servers trying to grab whatever free space they can off of your storage device(s). Since most virtualization solutions use different file system types — NTFS, VMFS-3, ext3, etc…, different virtualization solutions cannot efficiently make use of other virtualization solutions’ free space. There are of course loop holes, such as mounting other file systems as a network file system, but these solutions result in a degradation of speed and also incur the overhead of a file system on top of a file system.
Implementing multiple virtualization solutions also means that your staff must now be experts on each piece of software used. This expectation is most likely unrealistic and can result in system administrators that are proficient in many areas but are experts in none.
While there are no technical reasons you cannot utilize virtualization solutions from multiple vendors in one data center, there are many reasons why it makes sense to stick to one vendor. However, there are always exceptions. The trick is to simply be mindful of the pros and cons in using heterogeneous technologies and to make the decision that makes the most sense for your environment.
The brouhaha over VMware’s attack on Microsoft’s virtualization licensing has brewed up some good blogs.
“I guess this marks the beginning of a crazy roller coaster ride,” writes Andrew Dugdell on his ‘Dugie’s Pensieve’ virtualization blog. He doesn’t think Microsoft’s licensing story is as full of “doom and gloom” as VMware says. “Obviously all forms of virtualization licensing and interoperability is going to get better,” Dugdell wrote. “It has to. I don’t think the market/customers will tolerate anything less.”
VMware is “foaming at the mouth”, says Alex Vasilevsky, founder and CTO Virtual Iron Software, on Virtual Iron’s Virtualization Blog. He thinks VMware is the pot calling the kettle (Microsoft) black. He wrote: “Of course, if VMware truly felt that ‘customers require an any to any interoperability model’ then wouldn’t their virtual disks be in an open format, as opposed to the proprietary format they continue to use? (For what it’s worth, we’re using Microsoft’s VHD format.)”
On his virtualization.info blog, Alessandro Perilli predicts that VMware may feel the ire of its parent company, EMC. “While suggesting a pacific resolution of this case (which would require a public rectification from VMware), Microsoft is clearly recalling its partner EMC for the unprecedented attack of its virtualization subsidiary,” Perilli wrote. He notes that EMC plans to launch a VMware Initial Public Offering (IPO) this summer, “and a compromising of Microsoft partnership could lead to a remarkable damage for stock performance.” That’s an “undesired risk” for EMC, which hasn’t been in Wall Street’s good graces for a while, Perilli concluded.
Dugdell wants to move beyond the age-old software licensing arguments. “Here’s the exciting burning question, how much better will Virtualization interoperability get? How aggressive is that curve going to be? I want to see that curve so steep, you can just feel the gforces kicking in!”
Yesterday evening, Microsoft’s PR team sent out a statement attributed to Mike Neil, its GM for virtualization, responding to the whitepaper posted by VMware last week:
“Microsoft believes the claims made in VMware’s whitepaper contain several inaccuracies and misunderstandings of our current license and use policies, our support policy and our commitment to technology collaboration. We believe that we are being progressive and fair with our existing licensing and use policies and creating a level playing field for partners and customers. We are deeply committed to providing high-quality technical support to our customers who are utilizing virtualization technology. In addition, we are committed to working collaboratively with industry leaders to foster an environment of interoperability and cooperation that best serves our customers.
I agree with Ashlee Vance at the Register when he said “Microsoft has fought back against VMware’s meat with something akin to marketing bologna.”
The idea that VMware’s paper contains “several inaccuracies and misunderstandings of our current license and use policies” is tantalizing to a reporter, except that Microsoft would not provide a spokesperson to elaborate.
Where things get interesting, however, is in the next paragraph, when Microsoft brings up… EMC, VMware’s parent company:
“We believe it’s better to resolve VMware’s claims between our two companies so that we can better serve customers and the industry. EMC is a long-time partner of Microsoft. We’ve extended this courtesy to VMware due to our mutual customers and partnership with EMC. We are committed to continuing to collaborate with VMware as we have been doing on regular basis. Consistent with this, Microsoft believes that we will be able to accommodate a mutually agreeable solution between our two companies and clear up any existing misunderstanding with regard to the points raised in the whitepaper.”
Maybe it’s just me, but doesn’t it seem that Microsoft is invoking its “strong partnership” with EMC as a way of bringing the wayward VMware child back in to line?
VMware’s whitepaper Microsoft Virtualization Licensing and Distribution Terms has generated a flood of articles by the IT trade press, and SearchServerVirtualization.com is no exception (See ‘VMware criticizes Microsoft virtualization licensing‘). Now that the story is up, I’m left wondering whether in this case, is Microsoft really trying to stymie competition, as VMware contends, or is it also possible that Microsoft, like every other software vendor on the planet, is grappling with how best to approach software licensing in this brave new virtualization world?
In Microsoft’s defense, the company has made some very virtualization-friendly moves as of late. In October, it announced Windows Server 2003 Datacenter Edition, which allows for an unlimited number of Windows Server VMs running on a system. According to Microsoft’s Windows Server Virtualization Calculator, it’s more cost-effective to buy the unlimited virtualization license over Enterprise Edition after just nine VMs on a two-processor server. The company made a similar announcement last week with SQL Server 2005 Enterprise Edition — pretty cool.
The revelation that reassigning Windows Server licenses between hosts is prohibited more frequently than once every ninety days came as a surprise to everyone I talked to, so I’m wondering whether this is more of hypothetical threat than a reality? Have any actual VMware customers out there changed or discontinued their use of VMotion and Distributed Resource Scheduler to comply with this license provision? If that describes you, email me at firstname.lastname@example.org.
Thomas Ptacek writes about two ways virtualization complicates life for systems security people in his blog entry, Dark Reading on Virtualization Security.
First of all, he says, “you now face the spectre of guest-hopping attacks, which are vulnerabilities in your hypervisor that allow you to beat VM protection and gain access to other hosts. The driver for these attacks is that a hypervisor has to provide at least the illusion of a ‘ring 0’ for a guest operating system to run in.” Secondly, he adds: “If you’re on the same hardware as your target, you have significantly improved timing channels to pry encryption secrets out with.”
Fortunately, he has some ideas on how to handle these problems. So do the other writers for Matasano Chargen, a blog about information security.
Virtualization security is on our readers’ minds, too, and we’re answering their requests for advice. Check out Chris Wolf’s advice on virtual switch security on Virtual Server, VMware and XenExpress and the virtualization security series by Harley Stagner, in which he suggests ways to improve Microsoft Virtual Server security.
What aspect of virtualization security is bugging you? What should IT shops really be worried about?
This week, Microsoft revamped pricing for SQL Server 2005 whereby “Enterprise Edition” customers can run unlimited instances of SQL Server within virtual machines of any denomination — VMware, Microsoft Virtual Server, etc… Compare this with SQL Server Standard Edition, which is licensed per physical or virtual processor.
At first blush, this seems like a pretty good deal, kind of like the unlimited virtualization with Windows Server 2003 Datacenter Edition. But the more I think about it, the more I wonder — just how many folks is this really pricing really going to affect? First of all, how many SQL Server instances would one need to run per host in order for this deal to make economic sense? More to the point, how many shops are really running databases in virtual machines? And even if they are, don’t virtualization best practices state that we need to mix up our workloads?
Anyway, these are just some preliminary thoughts. If you’re running databases within VMs — particularly big honking I/O intensive ones — leave a comment; I’m curious to hear about how it’s working out.
Since I joined the site, I’ve watched our contributors help our tip section grow with some phenomenal series-length tips. To date, the best have been:
- Optimizing Microsoft Virtual Server 2005, by Anil Desai
- Getting started with VMware on Windows, by Andrew Kutz
- Microsoft Virtual Server from the ground up, also by Anil Desai
- Step-by-step virtualization, by Alessandro Perilli
- and Choosing the right virtualization solution, another by Andrew Kutz.
…at least in my opinion. Have you used them? Were they helpful? Comment and tell us. Also let us know what you’d like to see more of.
Just recently published a new guide by Alessandro Perilli, which talks about virtual machine backup, how to create failover structures, configure clusters and automate the provisioning of virtual machines.
Next up is a new series by Anil Desai. He gets in to detail about automating Virtual Server using Visual Studio .NET and VBScript.
Lastly, welcome to our blog! We’ve been talking about this for a while, and we’re all pretty excited about it. We hope you join right in and comment away. After all, it’s our readers that make our site.