As part of our continuing efforts to guide you through the jargon jungle, we would like to discuss redundancy, fault tolerance, failover, and high availability, and we’d like to add one more term: continuous availability.

Our friends at Marathon Technologies shared the following graphic, which shows how IDC classifies the levels of availability:


Redundancy is simply a way of saying that you are duplicating critical components in an attempt to eliminate single points of failure. Multiple power supplies, hot-plug disk drive arrays, multi-pathing with additional switches, and even duplicate servers are all part of building redundant systems.

Unfortunately, there are some failures, particularly if we’re talking about server hardware, that can take a system down regardless of how much you’ve tried to make it redundant. You can build a server with redundant hot-plug power supplies and redundant hot-plug disk drives, and still have the system go down if the motherboard fails – not likely, but still possible. And if it does happen, the server is down. That’s why IDC classifies this as “Availability Level 1″ (“AL1″ on the graphic)…just one level above no protection at all.

The next step up is some kind of failover solution. If a server experiences a catastrophic failure, the work loads are “failed over” to a system that is capable of supporting those workloads. Depending on those work loads, and what kind of fail-over solution you have, that process can take anywhere from minutes to hours. If you’re at “AL2,” and you’ve replicated your data using, say, SAN replication or some kind of server-to-server replication, it could take a considerable amount of time to actually get things running again. If your servers are virtualized, with multiple virtualization hosts running against a shared storage repository, you may be able to configure your virtualization infrastructure to automatically restart a critical workload on a surviving host if the host it was running on experiences a catastrophic failure – meaning that your critical system is back up and on-line in the amount of time it takes the system to reboot – typically 5 to 10 minutes.

If you’re using clustering technology, your cluster may be able to fail over in a matter of seconds (“AL3″ on the graphic). Microsoft server clustering is a classic example of this. Of course, it means that your application has to be cluster-aware, you have to be running Windows Enterprise Edition, and you may have to purchase multiple licenses for your application as well. And managing a cluster is not trivial, particularly when you’ve fixed whatever failed and it’s time to unwind all the stuff that happened when you failed over. And your application was still unavailable during whatever interval of time was required for the cluster to detect the failure and complete the failover process.

You could argue that a fail over of 5 minutes or less equals a highly available system, and indeed there are probably many cases where you wouldn’t need anything better than that. But it is not truly fault tolerant. It’s probably not good enough if you are, say, running a security application that’s controlling the smart-card access to secured areas in an airport, or a video surveillance system that sufficiently critical that you can’t afford to have a 5-minute gap in your video record, or a process control system where a five minute halt means you’ve lost the integrity of your work in process and potentially have to discard thousands of dollars worth of raw material and lose thousands more in lost productivity while you clean out your assembly line and restart it.

That brings us to the concept of continuous availability. This is the highest level of availability, and what we consider to be true fault tolerance. Instead of simply failing workloads over, this level allows for continuous processing without disruption of access to those workloads. Since there is no disruption in service there is no data loss, no loss of productivity and no waiting for your systems to restart your workloads.

So all this leads to the question of what your business needs.

Do you have applications that are critical to your organization? If those applications go down how long could you afford to be without access to them? If those applications go down how much data can you afford to lose? 5 minutes? An hour? And, most importantly, what does it cost you if that application is unavailable for a period of time? Do you know, or can you calculate it?

This is another way to ask what the requirements are for your “RTO” (“Recovery Time Objective” – i.e., how long, when a system goes down, do you have before you must be back up) and “RPO” (“Recovery Point Objective” – i.e., when you do get the system back up, how much data it is OK to have lost in the process). We’ve discussed these concepts in previous posts. These are questions that only you can answer, and the answers are significantly different depending on your business model. If you’re a small business, and your accounting server goes down, and all it means is that you have to wait until tomorrow to enter today’s transactions, it’s a far different situation from a major bank that is processing millions of dollars in credit card transactions.

If you can satisfy your business needs by deploying one of the lower levels of availability, great! Just don’t settle for an AL1 or even an AL3 solution if what your business truly demands is continuous availability.

In part one, we address thin provisioning and virtual volumes. Watching this video will help you understand part 2 of “What is Storage Virtualization” where we talk about how multipathing relates to virtual volumes and contributes to a highly available SAN solution.

Take a few minutes to learn what is required and what would be optional in a XenDesktop deployment, as well as how all the pieces would interact.

Of course, there are other ways to run multiple operating systems side by side on a client device, although they may not give you the level of performance that XenClient – because of its small footprint – brings to the table. The tricky part is figuring out how to manage that environment once the user unplugs the laptop from the network and takes it on the road. How do you patch it? How do you back up user data? What do you do if the laptop is lost or stolen? If one of the OS instances is corrupted, or accidentally deleted, how do you get it back?

That’s the job of the Citrix Synchronizer – a virtual appliance that runs back in your data center and communicates with your XenClient-equipped laptops securely (via SSL) over the Internet. But rather than try to describe to you in detail exactly how that all works, it’s probably easier to simply show you. So take a few minutes to watch our own Steve Parlee demonstrate the interaction between Synchronizer and XenClient.

Now on to the actual video itself. This week we talk about Citrix Merchandising Server and Dazzle. A couple of products that we think you should really look into as they can make your life a whole lot easier. Steve Parlee (Moose Logic’s Director of Engineering and guy in the video) tells you a bit about each product but also walks you through a quick demo of how they work.

• June 2, 2010, 9:00am – 9:30am Pacific Time – XenDesktop Editions & What’s Best for Me
• June 9, 2010, 9:00am – 9:30am Pacific Time – WAN Optimization for Branch Offices
• June 16, 2010, 9:00am – 9:30am Pacific Time – Secure Access
• June 23, 2010, 9:00am – 9:30am Pacific Time – Different Methods to Deliver Virtual Desktops
• June 30, 2010, 9:00am – 9:30am Pacific Time – What is Virtualization?

In the future you will always be able to find the most up to date schedule on our upcoming events page. Also if you every have an idea for a topic you would like to see us discuss, send an email to sales@mooselogic.com and tell us your idea.

1. I’m a PC
2. I have not been one of the lucky bloggers out there that has received a free iPad to review, so I have never actually played around with one.

As of right now I have no intention of buying an iPad. That’s not to say I will never own one or that I am not interested in trying it out, but the fact of the matter is that despite all the great toys that Apple makes, they still don’t like to share with the other kids.  I simply don’t like the idea of being in technology lockdown.  Apple holds strong to its closed proprietary control over all things Apple. This has been slightly improved with third party apps, but again your app’s fate is still left to Apple to decide. The more popular Apple devices become, the more and more I hear “I would love to not use Apple but the iPod/(iPhone) is the best  portable media device/(phone) available.”  So, in exchange for locking you in, Apple has been able to connect with consumers on a whole new level and create some of the best user experiences.  But that doesn’t mean I like being locked in.

Will the iPad be a technology hit and another win for Mr. Jobs? I don’t know.  Weak prediction, I know. Yet I do think that this is a big step forward as far as how we, the consumers, want to access technology. One need only to look at the growing number of internet capable devices. Facebook’s popularity has surpassed Google and porn. Conversations are starting with “Do you follow <insert screen name here>?” Clearly we want to be “connected” and smart phones and netbooks have given us this ability. We have opened Pandora ’s  Box wirelessly and there is no going back.

If you have yet to use an iPhone or iTouch you don’t know what you’re missing. Multi-touch interaction is awesome. Now some of you out there are saying, “My smart phone with Windows mobile has a touch screen, so what?” To which I say, “Would you rather drive a Ferrari or a Kia on the autobahn?” (side note:  this is not to say that Kia does not make a fine automobile, it’s just…it’s a frakin’ Ferrari people!).  The secret sauce is the user experience. It’s simple, it’s clear, it’s easy, some might even argue that it is dumbed down a bit, but most of all it’s fun to use. Video sharing on YouTube, Facebook status changes, Twitter updates, ESPN RSS feeds, or just surfing Craigslist are just some of the ways end users are trying to add fun to their boring workday. Fun sells!

Then there is the growing remote workforce. It is becoming less and less necessary for employers to provide a physical workstation to its employees. Companies like Citrix are starting to move to a BYOC (Bring Your Own Computer) program and simply provide a remote desktop to its users (read more of the blog or contact us to learn how this is done). More and more, the hardware we use for work is becoming the device we use for personal stuff. The line is getting blurred and devices that are coming out today need to be able to bring our work and personal lives together on a single device.

I am all for trying to keep the two separate and maintain a healthy balance between them, yet this is the exact reason they should be on the same device. Access your files from the gym or local coffee shop. Update your Twitter feed or look at family pictures on a cross country business trip. As the business world becomes smaller it is becoming difficult for us to disconnect from our jobs even while driving (and please use a hands free device if you do indeed do business from your car – and for your children’s sake, lay off the email and text messaging…a big traffic ticket is the least you’re risking).

Unfortunately, as consumers are becoming connected and getting used to doing business from anywhere, it forces businesses, and therefore their employees, to be on call. The demand for quick response has grown as more and more information is available to anyone, anytime, and at their finger tips. There is no longer a gatekeeper to information.  If you are trying to grow your business and be a leader while still maintaining a nine to five model, you are fighting a losing battle.  We already see how individuals have started to embrace the always-on mentality. They have found the freedom to work when and where they want while accomplishing their own personal goals.  (This of course is not an overnight switch and there will always be jobs that will never be able to offer this offsite option.)

So the biggest news to me is not the iPad release but rather the shift in what consumers want/expect from technology and the fact that we are getting closer to that.  Always connected, easy to use, and can help me work and play from anywhere. The iPad’s fate is one that time will tell but I don’t really see its business application so I’ll pass for now.  (And, yes, I know that you can run the Citrix Receiver on your iPad and connect to a XenDesktop or XenApp farm.  But you can also do that from a netbook that can also do stuff that today’s iPad can’t do.)

So here’s my list of interesting tweaks, stuff that might be helpful to a handful of you, or just stuff that I think is cool. (Cool does not always mean useful – but who doesn’t like cool stuff?)

1. Most of you have probably seen “Peek” (at least if you have a system that’s “Aero” display capable), but it’s still cool – and if you haven’t seen it, maybe this will be what it takes to get you to splurge on that new video card! If you hover above an application icon on the taskbar, a thumbnail of the app will pop up. If you hover over that thumbnail, you’ll get a “peek” at the full-sized app. And hovering over the “show desktop” icon in the lower right corner (oh, you didn’t know that the unlabeled button at the bottom right would show your desktop?) will temporarily display your desktop.
2. And have you heard of “shake?” If you have 20 windows cluttering up your screen but only want to focus on one, just click the window’s title bar and hold the mouse button down.  Now, shake the mouse from side to side.  All other windows will disappear, leaving just the one that you selected.  (Yes, you could also click “show desktop” and then select the one window you want to focus on, but that’s not as much fun.)
3. To open a new instance of a program from your task bar (say you want an entirely separate IE window) you can right click the icon on your task bar and select the app from there, or just hold down shift and left-click the icon.
4. Toggle between application instances: Ctrl + Click a taskbar icon. Let’s say you have five open Word documents. If you hold down the Ctrl key, you can cycle through them by repeatedly left-clicking on the taskbar icon.
5. Multitask with multiple monitors: Various combinations of Ctrl, Windows logo key, Shift, and Arrow keys. Do you use more than one monitor at a time? Now you can shift an open window to your other monitor in less than a second by pressing Shift + Windows logo key + left or right arrow. Here are some other combinations that might be handy:
• Ctrl + Windows logo key + arrow will move the window to whatever half of the screen you want. (Up arrow sends the window to the top half, right to the right half, etc.)
• Windows logo key  + Up Arrow maximizes the window, Down Arrow “un-maximizes” it again.
6. Windows 7 “God Mode” (use with caution): Right-click on the desktop, and choose “New Folder.” Then re-name that folder:
   “GodMode.{ED7BA470-8E54-465E-825C-99712043E01C}” The icon will change. When you double-click it, you’ll get a window with direct links to just about every configuration option imaginable. Yes, they’re all available elsewhere, but it’s kinda cool to have them all in one place.
7. Finally, if you’re missing the old Windows “Quick Launch” area (which Sid prefers over pinning icons to the task bar, because it takes up less space):
   1. Make sure you’ve got Explorer configured to show hidden files and folders
   2. Right-click an empty space on the taskbar, and select Toolbars -> New Toolbar
   3. Browse to C:\Users\%username%\AppData\Roaming\Microsoft\Internet
      Explorer  (Why would this setting be under Internet Explorer?  It’s just one of life’s great mysteries.)
   4. Highlight the Quick Launch folder and click the Select Folder button.
   5. To get rid of the title and text associated with your Quick Launch icons, unlock the task bar, right-click your new Quick Launch toolbar, and uncheck Show Text and Show Title.  You can also choose View -> Large Icons if you prefer.

   Note that Win7 will put the Quick Launch toolbar on the right end of the taskbar (next to the System Tray) rather than on the left.