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  1. CPU and memory load generation scripts

    I was asked today how to generate CPU and memory load on a Windows server. I remembered from my VMware ESX training a VBScript which generated load on the CPU, but had never seen a script to stress memory. So I hacked together a VBScript which has an infinite loop which just keeps creating large arrays and filling them with data. Eventually the script bombs with an out of memory error, just what I was after!
    Feel free to use the CPU loading script (thanks to VMware and Xtravirt) and memory loading script but please do NOT use them on production systems!

  2. The password store on Windows 2008 / Vista

    I always recommend a profile management system for Citrix XenApp installations; the free Flex Profile Kit is a favourite, but I recently implemented AppSense Environment Manager (EM) for profile management on Windows 2008 Server and found that Internet Explorer passwords were not being saved. After some investigation I found that the password store is handled very differently in Windows 2008 Server and Vista.
    In Windows 2008/Vista the password store in the user’s profile is not roamed, even though it is in the roaming folder… that makes lots of sense…
    From what I can gather the Microsoft method is to use Certificate Services which is configured via GPO and saves credentials to the user’s AD object. See this article and this article.
    From an AppSense EM perspective the “Manage Certificates” personalisation option saves IE passwords, so this is the easiest option.
    A second method of saving IE passwords using AppSense or Flex Profiles is to save the Protect folder from the user’s profile at logoff and restore it at logon. I have tested this and it works perfectly.
    The piece of data that needs to be saved from the user’s profile is the folder %userprofile%\AppData\Roaming\Microsoft\Protect

  3. Run cmd as SYSTEM on Windows 2008 Server

    Thanks to Jarvis for this one, to run a cmd window as the SYSTEM account on Windows 2008 Server, download PSExec from Microsoft and use this command:
    psexec -i -s %comspec%

    The previous method using AT does not work with Win 2008, nor does the schtasks command in Win 2008 do the job either.

    Easy when you know how.

  4. Full hard drive on Windows 2008 Server

    Today a production XenApp 5 Windows 2008 Enterprise Server ran out of disk space. I only added it to the farm yesterday at which time it had 18GB of free space, so I knew something odd was up. Checking the folder sizes it only took a few minutes to find the culprit:
    %windir%\system32\spool\spooler.xml

    This file was 18GB and the cause of the low disk space. Stopping the print spooler allowed me to delete the file and a Google search quickly explained how to stop this from occurring again, see here and here – basically it’s Windows Error Reporting going nuts.

    I’m adding this to the build for all Windows 2008 Server installs so this doesn’t occur again:
    reg add HKLM\System\CurrentControlSet\Control\Print /v DisableWERLogging /t REG_DWORD /d 1

  5. Client hypervisors, are they the missing VDI link?

    Citrix recently announced XenClient, their client side bare metal hypervisor. VMware announced their client hypervisor back in February and I would not be surprised if Microsoft was also developing a product. A bare metal (or type 1) hypervisor is a virtualisation layer which is installed directly on your hardware. Most of us are familar with server virtualisation, well client hypervisors are simply applying the same technology to desktops and laptops. A client hypervisor is more challenging to develop though due to the much broader hardware support needed: think graphics, audio, USB, firewire etc.
    So what’s the point? Why the race to bring out a client hypervisor? Because the client hypervisor could be the missing piece of the VDI puzzle. Today, if you implement a VDI solution what do you do with your mobile users or power users who need more resources than VDI can provide? Nothing, you leave them running a locally installed OS which is a different image (or possibly several images to accommodation hardware flavours) to the VDI users. This means greater management effort and costs as well as more difficult and complex troubleshooting.
    In the client hypervisor world everyone in your organisation can run the same OS image whether connected to a server based VDI instance or on a physical laptop or desktop. This will drastically simplify environments with follow on cost savings.
    Bring it on I say! I can’t wait to try out a client hypervisor.

  6. Citrix Stats using PowerShell and SQL

    Wow, I like what Alain has done with some PowerShell/SQL/Visual Studio tricks. I can see how this could be turned into a farm trending/capacity management tool. Check it out here.

  7. The cost of live migration: Did VMware miss an opportunity with vSphere?

    VMware recently announced vSphere 4, the replacement for ESX 3.5. When I read that new editions had been released for small business I thought VMware would include live migration (VMotion) functionality to compete with Citrix XenServer which includes live migration (XenMotion) for free. But the VMware vSphere editions comparison table shows VMotion availitility with Advanced, Enterprise and Enterprise Plus only. This leaves the small business Essentials, Essentials Plus and Standard editions without the ability to perform live migrations with VMotion. So what is the cost for a small business to purchase vSphere Advanced? U.S suggested list pricing is US$2245 per processor. So a dual processor, two server vSphere farm will be $8980 (I’ll ignore vCenter and Service and Support costs). Did VMware miss the boat by not providing VMotion in one of the Essentials editions? I feel that Citrix are strongly positioned in the small to medium business market with the features available for free.

    Now don’t get me wrong, I’m not saying Citrix have a better product than VMware. I believe the rich features and polished management interface from VMware are second to none. Although under the hood, at the hypervisor level I am undecided – prior to vSphere being release I was leaning towards XenServer being the superior hypervisor, but I have yet to see vSphere in full action yet, so I reserve my judgement.

    I believe VMware have given IT a very good reason to investigate XenServer by not lowering the cost of VMotion, especially in small and medium businesses.

  8. The cost of Live Migration: Did VMware miss an opportunity?

    VMware recently announced vSphere 4, the replacement for ESX 3.5. When I read that new editions had been released for small business I thought VMware would include live migration (VMotion) functionality to compete with Citrix XenServer which includes live migration (XenMotion) for free. But the VMware vSphere editions comparison table shows VMotion availitility with Advanced, Enterprise and Enterprise Plus only. This leaves the small business Essentials, Essentials Plus and Standard editions without the ability to perform live migrations with VMotion. So what is the cost for a small business to purchase vSphere Advanced? U.S suggested list pricing is US$2245 per processor. So a dual processor, two server vSphere farm will be $8980 (I’ll ignore vCenter and Service and Support costs). I think VMware missed the boat

  9. Automated XenServer host & VM shutdown

    A client is currently implementing Citrix XenServer 5.0 and had hit a snag trying to get the new XenServer hosts communicating with their APC UPS. They had read How to Integrate XenServer and APC PowerChute but the example given is very basic and not dynamic; the script needs to know the pool master and the names of all your VMs. But the script was a great starting point and with the XenServer CLI documentation I was able to create a dynamic shutdown script.

    The script runs on a physical box with XenCenter (or at least with the command line xe tool). A username, password and two XenServer IP addresses are specified in the script. Why two XenServer IPs? In case the first XenServer is down/has changed IP etc – a basic fall back plan. When the script runs it disables all hosts in the pool, shutsdown all the VMs in the pool and finally shutsdown all the hosts in the pool.

    For this particular client they have the APC software installed on the same physical box as XenCenter and have configured the software to run this script when the UPS reaches a critical level.

    Download the script here and use as you please – just leave my details at the top.

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