Category: Technology


Symptoms

Device Manager displays only non-Plug and Play devices, drivers, and printers when you click Show hidden devices on the View menu. Devices that you install that are not connected to the computer (such as a Universal Serial Bus [USB] device or “ghosted” devices) are not displayed in Device Manager, even when you click Show hidden devices.

Workaround

To work around this behavior and display devices when you click Show hidden devices:

  1. Click Start, point to All Programs, point to Accessories, and then click Command Prompt.
  2. At a command prompt, type the following command , and then press ENTER:
    set devmgr_show_nonpresent_devices=1
  3. Type the following command a command prompt, and then press ENTER:
    start devmgmt.msc
  4. Troubleshoot the devices and drivers in Device Manager.

    NOTE: Click Show hidden devices on the View menu in Device Manager before you can see devices that are not connected to the computer.

  5. When you finish troubleshooting, close Device Manager.
  6. Type exit at the command prompt.

    Note that when you close the command prompt window, Window clears the devmgr_show_nonpresent_devices=1variable that you set in step 2 and prevents ghosted devices from being displayed when you click Show hidden devices

Advertisements

In the Information Technology world, you often hear people say that IPv6 is “the worst” or it causes problems and breaks things with the high recommendation of disabling it.  However, the source of this recommendation is never clearly specified nor validated and there is significant reason to leave it enabled.

When you talk to Microsoft or attend seminars, you always hear them recommend to not to disable IPv6.  The explanation is located at the link below.  I love how Microsoft begins the explanation in this Q&A.

IPv6 for Microsoft Windows

http://technet.microsoft.com/en-us/network/cc987595.aspx

Q. What are Microsoft’s recommendations about disabling IPv6?

A.

It is unfortunate that some organizations disable IPv6 on their computers running Windows 7, Windows Vista, Windows Server 2008 R2, or Windows Server 2008, where it is installed and enabled by default. Many disable IPv6-based on the assumption that they are not running any applications or services that use it. Others might disable it because of a misperception that having both IPv4 and IPv6 enabled effectively doubles their DNS and Web traffic. This is not true.

From Microsoft’s perspective, IPv6 is a mandatory part of the Windows operating system and it is enabled and included in standard Windows service and application testing during the operating system development process. Because Windows was designed specifically with IPv6 present, Microsoft does not perform any testing to determine the effects of disabling IPv6. If IPv6 is disabled on Windows 7, Windows Vista, Windows Server 2008 R2, or Windows Server 2008, or later versions, some components will not function. Moreover, applications that you might not think are using IPv6—such as Remote Assistance, HomeGroup, DirectAccess, and Windows Mail—could be.

Therefore, Microsoft recommends that you leave IPv6 enabled, even if you do not have an IPv6-enabled network, either native or tunneled. By leaving IPv6 enabled, you do not disable IPv6-only applications and services (for example, HomeGroup in Windows 7 and DirectAccess in Windows 7 and Windows Server 2008 R2 are IPv6-only) and your hosts can take advantage of IPv6-enhanced connectivity.

 

 

There are nine server roles you can install on Server Core:

  1. AD DS – Active Directory Domain Services
  2. AD LDS – Active Directory Lightweight Directory Services
  3. DNS – Domain Name System
  4. DHCP – Dynamic Host Configuration Protocol
  5. File Services
  6. Print Services
  7. Streaming Media Services
  8. Web Server (IIS)
  9. Hyper-V

Server Core is built solely to run only these nine server roles.  Nothing else.

RAID Configuration Best Practices

Throughout my career, I have seen many different practices on which levels of RAID (Redundant Array of Independent Disks) to use.  This post is referring to the traditional RAID form as there are now a few new forms of RAID that I believe in the future will supplant the original type.  Here are my recommendations and best practices that have served me well through the years.

  • RAID 0 – fastest performance, but also highest chance of failure.  With one drive failure, you will lose the entire array.  Best used as a scratch disk and data that can be lost.
  • RAID 1 – optimal for operating system (OS) installation with 2 drives.
  • RAID 5 – not recommended for any arrays larger than a couple terabytes because of the high chance of an unrecoverable read error (URE) and tolerance of only 1 drive failure.  I have seen too many UREs with RAID 5 that prevent a successful rebuild.  A URE happens when there is corrupt data in the array preventing a successful recovery from a degraded state.  Requires a minimum of 3 drives.
  • RAID 6 – recommended for data stores where reads are more important than writes.  Tolerates 2 drive failures and significantly less chance of experiencing a URE.  Requires a minimum of 4 drives.
  • RAID 10 – most expensive, but has the best performance and resiliency.  Requires a minimum of 4 disks.  It is striped (for performance) and mirrored (for redundancy).

NOTE: RAID is not a replacement for backups.  A good backup strategy that involves testing the backup is a necessity for a production environment.

Also, do yourself a favor and never use RAID 5.  I’ve seen too many failures, headaches and trouble caused by its usage.

Another type of RAID that I recommend and is my first recommendation is using a ZFS file system that has similar options, but better performance and resiliency with background data scrubbing.  The generic name for that type of RAID is called RAIDZ.  I’ll touch on examples and further explanations of this new state-of-the-art form of RAID in another post.

Installation

Download Hamachi2 deb from the LogMeIn download page.
https://secure.logmein.com/US/labs

When the download completes:

  1. Open up a terminal window.
  2. Change to the directory housing the newly downloaded .deb file.
  3. Issue the command

    sudo dpkg -i logmein-hamachi_XXX_xxx.deb

    (Where XXX is the release number and xxx is the architecture for your hardware). NOTE: If your installation doesn’t complete, you might need to open up Synaptic to “fix” the broken packages. This is an easy way to catch all of the dependencies.

  4. Type your sudo password and hit Enter.
  5. Allow the installation to complete.

Now you are ready to install the GUI.  Instead of downloading a .deb file, we are going to add the PPA for Haguichi to our system.  Once the PPA is added, Haguichi can be installed using apt-get. Here are the steps:

  1. Open up a terminal.
  2. Issue the command

    sudo add-apt-repository ppa:webupd8team/haguichi

  3. Issue the command

    sudo apt-get update

  4. Issue the command

    sudo apt-get install haguichi

Haguichi client has been more reliable than Hamachi GUI.

Connect to, or create a VPN network

Click Applications | Internet | Haguichi. When the Haguichi window opens (at left), click Client | Join Network.  A new window will open where you can enter the credentials for the VPN you want to join.

You can also create a new network by clicking Client | Create Network.  You will have to enter a name and a password for that network.

Make sure your password follows standard strong password practices. Do NOT create a week password for a VPN network connection.

Now set the proxy settings in your browser to use the secure Hamachi+Privoxy proxy.

Install and Setup Privoxy

Privoxy is a free, open source web proxy.  It will be installed on your machine that you would like to connect to as your proxy.

  1. Download Privoxy from Sourceforge for your system and install. Privoxy is available for Windows, Mac, and Linux.
  2. After you’ve installed Privoxy, launch the application. (If you’re running a firewall, you may need to give it access to open a port.) In Windows, Privoxy loads as a blank window.  It doesn’t mean it isn’t working and you can close this window; Privoxy will still be running in your system tray.
  3. Configure Privoxy to transmit traffic through your Hamachi setup
  4. Right-click Privoxy in the system tray and select Edit > Main Configuration.  Notepad will open with a text file called config.txt; this is Privoxy’s main configuration file.
  5. Press Ctrl+f and search for listen-address 127.0.0.1:8118. Most of the code is commented out with # in front of it.
  6. Type listen-address followed by the IP address created by Hamachi (i.e., listen-address 25.xxx.xxx.xx:8118).
  7. Save config.txt and restart Privoxy.

Chrome Privoxy Configuration

How to Secure and Encrypt Your Web Browsing on Public Networks (with Hamachi and Privoxy)

  1. Install the Proxy Switchy extension. Once installed, it should automatically open a new tab with its options.  (If it doesn’t, right-click the Proxy Switchy icon in your toolbar and select Options.)
  2. Enter a profile name—(i.e. Privoxy.
  3. In the HTTP Proxy box under Manual Configuration, enter the Hamachi VPN IP address to the computer where you set up your proxy. Set the port to 8118.  (Remember: Hamachi needs to be running on both computers when you want to use this proxy, and you can get the IP of any other computer on your Hamachi network by right-clicking the computer name and selecting Copy address.)
  4. Click Save and you’re done.

Whenever you want to browse using your secure proxy—just click the Proxy Switchy icon in Chrome, then select your Privoxy connection.

Conclusion

If you need to connect a Linux machine to a Hamachi VPN (or need to quickly create a VPN network), Hamachi2 and either Hamachi GUI or Haguichi are fantastic options. The setup time is short an the tools are user-friendly.  OpenVPN is another good option, but is much more complex to configure.

However, the source code of the Haugichi software is 100% open source, it does rely on the Hamachi service which uses non-open source software.

Linux ‘rdesktop’ Command

Linux is great, but there will more than likely always be a need to remote desktop into a Windows machine.

Open a terminal window and type the following command to initiate a session:

rdesktop [machine/ip address] -flag

 

Plan for Expansion

Virtualization deployments along with any technology typically need to grow with the business. Previously, this was accomplished by racking more servers or overbuying initially.  Because workloads are now consolidated onto fewer servers in clusters there are a few additional options.  All of them are below:

  • Overbuy initially.
  • Scale up by adding hardware to existing hosts including RAM, CPU, and hard-disk space.
  • Scale out by adding hosts to spread the workload.

Clusters typically have a maximum amount of nodes that can be included.  Newer versions up the ante:

  • Windows Server 2012 – 64 nodes
  • Windows Server 2008 R2 – 16 nodes
  • Windows Server 2008 – 8 nodes

The old and original VHD (Virtual Hard Disk) format was first introduced by Connectix which was later bought by Microsoft and turned into Microsoft Virtual PC.  It contains everything a physical HDD (Hard-Disk Drive) would contain including disk partition and a file system (NTFS, FAT32, etc.)  It is the storage foundation for VMs (virtual machines).

VHDX is the new file format bringing several improvements to match Hyper-V 3.0 in Windows Server 2012’s increased processing and memory capacity.

Bigger, Better & Faster

  • Size – Format supports up to 64 TB which is 32 times more than the 2 TB limit found in VHDs
  • Protection Against Disk Corruption – provides corruption protection during power failures for VHDX files by a logging mechanism for the updates of the VHDX metadata structures.
  • Support to run on large sector disks without a performance hit.
  • Larger block sizes up to 256 MB for dynamic and differencing disks resulting in better performance with workloads that allocate in larger chunks such as RAW images and videos.
  • Stores custom metadata in the VHDX file including OS version, patches applied or whatever you can think of up to 1024 entries of 1 MB.
  • Takes advantage of Offline Data Transfer (ODX).

ODX

  • Speed improvements of creating VHDX files with the ability to offload to a SAN if the storage vendor supports ODX.
  • Merge and mirror operations are also offloaded to hardware which is specifically for merging snapshots or live storage migration.

TRIM/UNMAP Support

According to documentation we get “efficiency in representing data (also known as “trim”), which results in smaller file size and allows the underlying physical storage device to reclaim unused space. TRIM requires physical disks directly attached to a virtual machine or SCSI disks in the VM, and TRIM-compatible hardware as well as Windows Server 2012 on hosts & guests.

Check out the Server & Cloud Blog on TechNet where it shows impressive performance and scalability with the latest version of Hyper-V where there is support for up to 64 vCPUs, 1 TB of memory for VMs, and a new VHDX format supporting disk capacity up to 64 TB.

The key findings from ESG Labs were:

  • With Windows Server 2012 Hyper-V’s new support for up to 64 vCPUs, ESG Lab took an existing SQL Server 2012 OLTP workload that was previously vCPU limited and increased the performance by six times, while the average transaction response times improved by five times. 
  • Manageably-low Hyper-V overhead of 6.3% was recorded when comparing SQL Server 2012 OLTP workload performance of a physical server to a virtual machine configured with the same number of virtual CPU cores and the same amount of RAM.

3301.SQL 2012 on WS 2012 Hyper-V Graph 1.PNG-550x0 6012.SQL 2012 on WS 2012 Hyper-V Graph 2.PNG-550x0

http://blogs.technet.com/b/server-cloud/archive/2012/11/08/windows-server-2012-hyper-v-delivers-on-scalability-and-performance-for-virtualized-enterprise-applications.aspx

  • Two editions, Standard and Datacenter.
  • Each license covers up to two physical processors.
  • Editions differentiated by virtualization rights only (two for Standard; unlimited for Datacenter).
  • Standard licenses can be stacked on one server.
  • The most notable feature that is now available in Standard edition is: Windows Server Failover Clustering
  • A license is assigned to the physical server and not a virtual machine.
  • A license cannot be split across multiple servers.

Downgrade Rights

  • Windows Server 2012 Datacenter edition will have the right to downgrade your bits to any prior version or lower version.
  • Windows Server 2012 Standard will have the right to downgrade your bits to any prior version of Standard, Enterprise or Essentials editions.

Enterprise edition is retired as part of the Windows Server 2012 release and as a result the product lineup has been simplified down to two editions.

Software Assurance Step-Up benefit allows upgrades from lower editions to higher.

End of Architecture

A site about architectural iconography

Made in Kachchh —

Story-telling from Western India

The AdStage Blog

Cross-channel Online Advertising

WordPress.com

WordPress.com is the best place for your personal blog or business site.

The WordPress.com Blog

The latest news on WordPress.com and the WordPress community.

%d bloggers like this: