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March 3rd, 2010 by Andrew H.
With all of the talk about virtualization lately, many organizations are ready to pick up everything and virtualize it. After all, it’s the thing to do! Here are some things to keep in mind before virtualizing everything in sight:
1. Don’t virtualize highly utilized servers
One of the biggest benefits of virtualization is being able to make better use of your hardware. Adding virtualization doesn’t add more horsepower to your server; in fact, it’s another layer that can reduce performance. If you have a service that is already using most of the resources on a fairly powerful server, there’s a good chance that it might not be the best candidate for virtualization. If you decide to virtualize a workload that is disk intensive, consider using a raw pass through disk instead of a virtual hard disk to improve disk I/O performance.
2. Don’t cluster a cluster
Many virtualization platforms allow you to provide for some level of high availability for your VMs. Applications can provide a similar feature, but use caution when using them together. Generally speaking, services clustered with Microsoft Cluster Services that use a shared disk should never be configured in a way that makes the virtual machines automatically move from one server to another. Having multiple levels of failover might cause unexpected results and unnecessary disruptions to users.
3. Don’t virtualize everyone’s desktop (and expect to save money)
There are some legitimate benefits to virtualizing desktops, but cost is usually not one of them. No matter where a desktop is, users still need something to access it with. Server hardware is also inherently more expensive than traditional desktop hardware. On the other hand, virtualized desktops can be a great fit for remote employees, as backup workstations, or to ensure standardized desktops. In most cases, however, a Remote Desktop Services session host (previously Terminal Services and available only on Windows machines) can provide a cheaper and more efficient alternative provided that users don’t require administrative privileges.
4. Don’t create conflicting dependencies
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Tags: virtualization
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January 27th, 2010 by Andrew H.
Virtualization offers advantages that take many forms, but with it can come challenges because virtualization lies. The basic premise of virtualization is that the operating system running on a virtual machine is presented with hardware that doesn’t really exist. Performance monitoring on any platform can be complicated and influenced by a variety of factors, but measuring performance on a system that involves lies is even harder. Luckily, most virtualization products have special ways to gather more accurate system performance. This article will focus on Hyper-V, but similar tools are available for other platforms.
Disk
Since Hyper-V supports dynamically expanding disks, the disk capacity of the virtual machine can be misleading. When dynamically expanding disks are used, plenty of free capacity might appear to be available on the virtual machine, but the host’s free space could be very low. For this reason, it’s important to monitor the available capacity of the Hyper-V host as well as the virtual machines. Disk performance can be monitored accurately in Hyper-V virtual machines the same way as physical machines.
Network
Multiple virtual machines can share the same network adapter. Since each virtual machine can only report its own usage, it’s important to watch the usage of all virtual machines. VMs will also report that they are on a 10gbps connection; however, the bandwidth of the link will always actually equal the bandwidth of the external link.
Processor
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Tags: Hyper-V, monitoring, virtual machines, virtualization
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December 23rd, 2009 by Andrew H.
Have you ever experienced resource contention on your server? If you have, a Windows feature called Windows System Resource Manager (WSRM) might help minimize the impact of those situations. WSRM allows you to control CPU and memory resource allocation to applications, terminal services users, and IIS Application pools when they are scarce.
CPU limits in WSRM kick in when CPU utilization exceeds 70%. Instead of limiting CPU usage, Windows ensures that processes receive at least the amount of processing power specified. You can think of it as a sort of QoS for processors. While being able to set process priority is a feature many people are aware of, it did not provide the level of granularity that many environments require. WSRM allows for different resource policies in different situations. For example, different policies might apply on the weekend than during the workday to allow your server’s priorities to match the priorities of the business.
In a Terminal Services environment, one user could potentially use all of the available processing power, causing other user sessions to become extremely slow. With WSRM, it is possible to guarantee a user a certain amount of processing power or divide it equally among users—all without wasting available resources. IIS application pools can be managed the same way, allowing administrators to prioritize websites similarly to applications.
Whether you have a misbehaving process you need to reign in, a power user slowing down a terminal server for other users, or just need a better way to manage your server’s resources, WSRM could be the tool that keeps your critical applications running smoothly.
Tags: IIS, memory, Windows, Windows System Resource Manager, WSRM
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October 21st, 2009 by Andrew H.
Windows has long been under criticism by Linux users for its lack of a full featured command line interface with real scripting capabilities. After all, have you ever tried to do something complicated with a batch file? It’s not usually an enjoyable experience. Want to use pattern matching? You’ll need a third-party app. Want to manage another application? You’d better hope it has a command line administration tool. Microsoft has always built rich graphical administration tools, but if you wanted to use the command line, you’d quickly find your hands tied.
But that was the past.
Enter PowerShell
I’m happy to see that Microsoft has woken up to the needs of their users. If you’ve installed any of Microsoft’s recent server products, you have undoubtedly seen PowerShell. In fact, new Microsoft Server products such as Windows Server 2008 R2 and Exchange 2010 have been designed to ensure that all actions that can be accomplished through a graphical management tool can also be completed through PowerShell.
Many graphical tools actually execute PowerShell scripts on the back-end, and give administrators the opportunity to view them before executing them. Many items that are not exposed through graphical management tools are available from PowerShell, and the naming syntax for commands and other objects are consistent between products. Those familiar with Linux systems will find that many common commands are aliased right out of the box, such as man. Yes, I said man—Microsoft includes thorough documentation for every cmdlet (that’s what they call each command).
Enter PowerShell 2.0
If that’s not good enough for you, the new features in PowerShell 2.0, which was released with Windows Server 2008 R2, might catch your eye.
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Tags: cli, powershell, scripting, Windows Server 2008 R2
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August 12th, 2009 by Andrew H.
With a new version of nearly every product always on the horizon, you might be wondering if Exchange 2010 is simply another ploy to squeeze your wallet dry. After all, it’s just e-mail! But for anyone who has lived through Exchange migrations in the past, Exchange 2010 has a few features that might make your next migration a little bit simpler, while also giving your users something to rave about. Just a quick disclaimer, though: Exchange 2010 is still under development. Some features may change between now and when the product is released.
#1: Online Mailbox Moves
As you know, moving data takes time. Users with large mailboxes are usually the ones that are least willing to wait patiently while their mail moves (especially if that mailbox is moving to another location across a WAN connection!) In previous versions of Exchange, users were unable to access their mailbox while it was being moved. Users who were in cached mode and had Outlook open prior to the move were still able to access old mail, but new mail wasn’t available until after the move.
In Exchange 2010, mailboxes can be moved between different Exchange 2010 databases without any interruption in service. While this doesn’t directly help migrations from older versions of Exchange, organizations moving a mailbox to another site can first add an Exchange 2010 server to host the mailbox at the existing site in order to reduce downtime while data travels across slower connections.
#2: Database Availability Groups
One of the biggest complaints that I have heard from companies seeking a highly available Exchange 2007 solution is that doing so required a minimum of 4 servers. This is because no other roles could be installed on the same server as a clustered mailbox server. Doubling the number of servers adds cost, no matter how you slice it.
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Tags: data migration, email, exchange 2007, exchange 2010, high availability, owa
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