VDI Paging Files – Big? Small? Or None At All?

VDI - Paging FilesFor the past few months I have been spending a lot of time looking at the performance of Large VDI environments, where the problems lay and where performance can be improved.

When designing VDI environments, a couple of things that you should consider are the .vswp file and the GuestOS paging file. In this article I am going to focus on the Paging file and hopefully in the not so distant future I will write a post about the .vswp file in a VDI environment.

What is point of the paging file (also known as the pagefile.sys)?

RAM is a limited resource. Virtual memory was introduced to help remove that limit.

Most modern operating system now use Virtual Memory. Virtual memory is a memory management technique. Applications running on a GuestOS reference memory using virtual memory addresses which are then automatically translated into RAM addresses by the hardware. These virtual memory address spaces are divided in pages or block, usually of 4KB. 

If RAM resource is exhusted, the operating system will move 4KB pages of the virtual memory onto the computers hard disk to free up the physical memory (RAM) for other processes. In Windows operating systems, these pages are stored in the pagefile.sys. 

A good way to think of this is;

Imagine a restaurant that has just open for the evening. When customers (Processes) arrive they get allocated a table (RAM) to sit and eat at. As the night goes on the restaurant get busier and free tables (RAM) begin to run out for the new customers (Processes) coming through the door. To free up spare tables (RAM) the waiter asks customers (Processes) who have finished eating if they wouldn't mind moving to the bar (Virtual Memory) where they can continue drink.

Without the paging file, if the physical memory becomes full, applications including the operating system will have to waiting until physical memory becomes available before it can be stored in RAM ready for the CPU to process. As you can imagine this causes massive performance problems.

In summary, you NEED to have a paging file.

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My Last Year = Desktop, Desktop, Desktop

desktop madness

I'm pretty sure all of you know I work for VMware's PSO. But did you know that for about the past year I've been specializing in VDI, specifically View? Probably not. Not a lot of people know that! I didn't know that people didn't know that, until recently at a few vBeers events I've been telling people what I've been getting up to and everyone was quite surprised. So I thought I'd share some of my experiences with you.

The two main types of engagements I've been working on are View Plan and Design and VDI Troubleshooting/Healthchecks. All of the engagements mentioned are 1000+ seat environments, all large scale and some global.

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Free VMware View training!!

I don't normally post things like this on my blog, but I feel that these courses could offer real value to people who are currently looking into VDI or have just installed it and looking to optimize it for their environment. I will be one of the experts on the on the bootcamp community pages, so I look forward to your questions.

Starting July 19 through July 29th, join the VMware VDI experts for a FREE 9-part bootcamp training series. In these online sessions-VMware will show you how to get started and successfully roll out and deploy your virtual desktops and applications. You’ll learn about key design considerations, storage and networking best practices, PCoIP tuning and how to optimize your base image. They will also touch on VMware's security server for PcoIP, how you can take advantage of powershell to write your own scripts and much more.

Every day VMware will publish a new 45 minute video for you to view. The VDI experts will be on the View bootcamp community pages throughout the course of the July bootcamp to answer any questions and jump in any discussions that come up. VMware will lock the discussions each night and move on to the next video.

At the end of this bootcamp, you will have a good understanding of the VMware View solution, how to roll it out and how to optimize View in your environment. Customers and partners can also register to receive a FREE e-book which is a collation of all of the presentations used during the bootcamp.

And don’t worry if you can’t make it to the session on July 19th-29th-because we will be making these trainings available on-demand and locking all the threads so you can come back and view these at any time in the future.

Become a Bootcamp Survivor by tuning in each day

In order to qualify to become a “bootcamp survivor” you will need to log in and post a discussion thread in any of the bootcamp discussion forums. Qualified community IDs will be posted on the “Bootcamp Hall of Fame” page at the end of the bootcamp.

Bootcamp participants can also qualify for extra community points by blogging about the bootcamp over the course of the program. Post a link to your View Bootcamp related blog post in the bootcamp discussion forum to qualify for an extra 10 points per post, which will be awarded at the end of the program.

Find out more today!

Thin Client vs Zero Client

Thin vs Zero ClientsI was reading a discussion on an internal mailing list today about the differences between Thin and Zero desktop clients for VDI. I thought I would summaries the discussion and share it with you as it certainly helped to get it clear in my mind.

Zero Client

  • A Zero client is a special purpose / built client that uses a SoC or FPGA.
  • It is upgraded using a  firmware image. (Think of it like your  WiFi router.)
  • They all have software and they all run an OS.
  • The Teradici zero client for example runs a RTOS ( Real Time OS ) called Thread-X

Thin Client

  • A Thin Client is a device that has a stripped down custom OS, customized Linux OS or OEMed Windows Embedded OS. 
  • The image is typically larger than a firmware payload and in some cases a little more difficult to distribute depending on the management tools.
  • Some will argue they need to be managed / patched more and in some way that is true.

An example of a Thin Client would be like VDI Blaster where you have a tiny OS installed on a PC which has only one function and that's to get you to your virtual desktop.

In Summary

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VMware View: Transfer Server Functions

Summary 
I thought I'd put together some notes on the VMware View Transfer server as there doesn't seem to be to much information easily available on this feature of View.  Essentially it is used to Check-Out and Check-In virtual desktops, allowing them to be used in Local-mode (Offline). I want to show you in a bit more depth what happens when you Check-in, Check-out, Replicate and Rollback your virtual desktops.

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VMware View Desktops: IDE or SCSI? BusLogic, LSI Logic or PVSCSI?

confusedI've seen and had many discussions around this topic when discussing VMware View desktop design, so I though I'd gather as much information as I could to help you decide. 

From the information below, I would personally recommend using the following:

  • Windows XP: LSI Logic Parallel or SAS
  • Windows 7: LSI Logic SAS 

The PVSCSI controller will be the controller of the future so you may also want to keep this in mind. Of course you can make your own decisions. Most of the points made are desktop focused, however most will apply outside of a View environment.

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