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One of the criticisms that’s been leveled at XenDesktop by its competitors is that it is too complex – too many components that have to be configured to get everything to work. And while that’s partially true, it’s not the whole story. As we’ve discussed in previous posts, XenDesktop is extremely flexible in that it allows you to mix and match different kinds of virtual desktops in your environment to best meet the needs of various groups of users. As you bring more kinds of virtual desktops into the mix, you add more infrastructure components to manage them. More infrastructure components = more complexity but also more flexibility.

If you don’t need all that flexibility – if, for example, you just want to deploy “classic” VDI, by which I mean a bunch of virtual PCs running on the hypervisor of your choice – then you don’t need all that complexity, either.

In this video, Dan Feller of Citrix presents a reference architecture for a straightforward VDI deployment of up to 500 users. The video takes about 50 minutes to watch, but it’s worth your time. You’ll learn some interesting things.

For example, you’ll note that Dan is recommending that the XenServers in the XenServer pool that supports the virtual Windows 7 machines should have local disk drives, in a RAID 10 configuration, that will be used for the local host cache for the provisioned Windows 7 systems, for two reasons: First, it’s less expensive than using SAN storage. Second, the limiting factor for how many virtual PCs you will be able to run on a XenServer host is not processing power, and it’s not RAM – it’s IOPS. And he walks you through the calculation of how many functional IOPS the local storage on the XenServer can support, and how many virtual desktops you can therefore reasonably expect to support.

In fact, my only reservation about this video is that, like just about every other discussion I’ve seen regarding Windows 7 virtualization, it doesn’t mention the Microsoft license activation issue that’s inherent in provisioning Vista and Windows 7 desktops, the need for the Microsoft Key Management Service, and the nuances of getting KMS to work properly. But we’ve pummeled that issue elsewhere in this blog.

So, with that in mind, heeeerrrrrreeee’s Dan (P.S.: the audio doesn’t start until about 15 seconds into the video):

Moose Logic has been building and supporting networks for a long time. And during most of that time we’ve had a real love-hate relationship with most of the backup technologies we’ve implemented and/or recommended.

Tape backups – although they are arguably the best technology for long-term archival storage – are a pain to manage. Tapes wear out. Tape drives get dirty. People just don’t do test restores as often as they should. As a result, all too often, the first time you realize that you’ve got a problem with your backups is when you have a data loss, try to restore from your backups, and find out that they’re no good.

Add to that the astronomical growth in storage capacity, meaning that all the data you need to back up often won’t fit on one tape any more. So, unless you have someone working the night shift who can swap out the tape when it gets full, you’re faced with…

  • Buying multiple tape drives, which typically means you’re going to spend more on your backup software. And if your servers are virtualized, where are you going to install those tape drives?
  • Buying a tape library (a.k.a. autoloader), which can also get expensive.
  • Changing the tape when you come in the next morning, which means that your network performance suffers because you’re trying to finish the backup job(s) while people are trying to get work done.

Then there’s the issue of getting a copy of your data out of the building. Typically, that’s done by having multiple sets of tapes, and a designated employee who takes one set home every Friday and brings the other set in. If s/he remembers. Or isn’t sick or on vacation.

Backing up to external hard drives is a reasonable alternative for some. It solves the capacity issue in most cases. But over the years, we’ve seen reliability issues with some manufacturers’ units. We’ve uncovered nagging little issues like some units that don’t automatically come back on line after a power interruption. And they’re not necessarily the best for long-term archival storage, unless you keep them powered on – or at least power them on once in a while – because hard disks that just sit for long periods of time may develop issues with the lubrication in their bearings and not want to spin back up.

But we’ve finally found an approach that we really, really like. One that, as one of our engineers said in an internal email thread, we actually enjoy managing. In fact, we like it so much we built a backup appliance around it. It’s Microsoft’s System Center Data Protection Manager (SCDPM).

In this installment of the Moose Logic Video Series, our own Scott Gorcester gives you a quick overview of SCDPM 2010:



For more detail on how it works, check out the description of our MooseSentryTM backup appliance.

Watchguard LiveSecurity has released an urgent security alert for an email worm. It generally arrives with one of the following subject lines:

  • “Here you have”
  • “Just for you”
  • “This is the Free Dowload Sex Movies, you can find it Here”

The email contains a link to what appears to be a PDF document or WMV video, but is actually a link to a malicious Windows screen saver (.SCR) file. If you run the malicious .SCR file, it…

  • Copies itself to your Windows directory as CSRSS.EXE (the legitimate CSRSS.EXE is actually in your Windows\System directory), and modifies the Windows registry so it can restart after a system reboot
  • Sends itself to your email and IM contacts
  • Copies itself to mapped drives and removable USB media
  • Tries to disable popular security applications
  • Downloads and installs various other pieces of malware
  • Steals sensitive information (including passwords cached in your Web browser)

This worm does not appear to use any new techniques, and should be detected by most major antivirus vendors, so it is not cause for panic. You should, however, make sure you have the latest AV signature updates installed on your systems. Also, remind your users never to open unexpected attachments or click on unexpected Web links, even if they appear to come from friends, co-workers, or other trusted parties. The bad guys appear to be spamming this very aggressively, and it only takes one user to cause you a lot of headaches.

Back with another Moose Logic video for your viewing pleasure. In this installment, our own Steve Parlee, Moose Logic’s Director of Engineering, talks about SAN storage repository design concepts, and the effects your design choices have on things like snapshots, disk usage, and overall performance. In the process, you’ll also learn what we consider to be “best practice,” and some of the reasons why. As always, your comments will be appreciated. Enjoy!

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