P to V practices

P to V practices

Hi all,

     Having gone through two large scale datacenter consolidations now,  I found a really good procedure to help facilitate the arduous task of virtualizing hundreds of servers in a relatively short timeframe.  The keys are to do the proper amount of pre-conversion homework and also to do the post migration tasks thoroughly to optimize the virtualized server to run in a VMware environment rather than the vendor configured running environment.

     The best combination of tools I have found are VMware Capacity Planner, VMware Converter, and a good set of guest OS skills.

The VMware Capacity Planner will go out either by hostname or IP address ( or IP address range, or even entire subnet) and gather statistics and performance metrix about the physical hosts awaiting to be converted to virtual.  It can take a while to run as it gathers perfmon data about processor, memory, network, and disk utlilization and then plots it against time.  This is nice in that it allows you to see the machine at idle or low load, and also its load at high or peak utilization times.  Once this has been performed you can set aside the appropriate resources for your hosts or clusters and prepare your strategy for migration.

     A couple of key issues that you will want to find out prior to conversion are :

1.  The original or physical MAC address of the host to be converted

2.  The IP, DNS, NTP, and any other current network settings

3.  The raid configuration type, especially in Linux.  Typically if you see a software RAID in Linux, you are going to see the hard drives fail to convert due to the mdadm config.

4.  Know the Local Admin password.

     Now that you have the prepared your resources and pre-conversion specs in regards to the above mentioned 4 issues ,  you can begin to roll out the conversions.  you can, if you still have your Capacity Planner running use it to convert the hosts,  or, as I prefer,  plan out and schedule your migrations accordingly.  Each company will have different SLA's and different windows for maintenance, so depending on your flexibility, you can schedule around that.  However,  it is easy to perform the conversions and cross over to virtual while only missing a single ping if your careful, keeping downtime null.

     i use VMware Converter to convert the VM.  You must know the local admin password, and be able to reach the VM either by IP address or Hostname in order for Converter to be able to install the agent and perform the virtual driver substitutions.

     So,  open up converter,  select select the OS of the physical host, Windows or Linux,  populate with the proper credentials, admin or root works best.  At this point it will go out and produce a brief inventory of the physical machine and prepare for the conversion.  It installs an agent on the host OS,  and for older flavors such as windows 2000 or early RHEL Kernels, it will require a guest reboot.  This is rare though and you wont see it very often.  Once the agent is installed you will be able to view and edit the configuration of the VM.  You can see the listed hardware and see the virtual devices and device configurations to be applied.  Here is the first key.. I always disable the NIC's right away.  Since your physical device is still powered on, connected to the network, registered with DNS, and operational,  you dont want your unpolished converted VM to come online and cause an IP confilict or DNS resolution issue.  So,  always disable the NIC's on the conversions.

     Once the conversion is complete,   login to the guest as local admin and install VMware Tools.  this as you know,  allows for mouse and keyboard mobility, better display, and a bunch of other optimization options that help the VM operate, such as hardware acceleration...etc.

This will require a reboot of the guest vm in windows,  a restart of the services only in Linux.

     Once this is completed,  I perform the two following steps :

     1. Log into the VM and uninstall any residual software related to the vendor of the hardware the machine originally resided on.  For example if it was on an HP Proliant DL 380,  you can remove the bundled HP management and configuration software, as you are no longer on HP hardware, rather running off of a HyperVisor that substituted virtual drivers for physical ones.  So,  this clean up of software will streamline your installation and reduce any sort of conflicts affiliated with multiple systems management agents.

     2. Remove any physical or legacy drivers.  In windows you can issue the following command to display these in Device Manager.

set devmgr_show_nonpresent_devices=1

then to start device manager

start devmgmt.msc

     Now you will see the un-present or not used devices listed here with a light grey hue.  You can simply right click and uninstall these.  There may be several of them.  It is a key step in reducing conflict between the virtual and physical devices left configured post conversion.  Some issues you might see if this is not performed is being able to properly configure your NIC due to the IPaddress already being used on a NIC on the VM,  even though this NIC was physical and is no longer present, the configuration still has this IP and information configured so,  you can not apply it to another NIC until uninstalling it from the previous or physical adapter settings.

     Once this is complete you can go into your network adapter or into your networking-scripts config file for Linux and populate your previously recorded Networking information,  NTP, DNS, WINS, IP, Gateway, SNMask,....etc.  These settings will now stick and if you so choose you can spoof the MAC to match the original now as well.  This is usefull when dealing with a Flex LM license or any other piece of software or licensing that is MAC bound.

Finally you can reboot the VM to save all the config changes and once it is back online you can check the box for connect network.  I would at this point open up a continuous ping to the Physical Machine and login to it,  shut it down and wait for your  ping to time out once,  then hit apply to the screen where you enabled your VM nic, and watch your pings get replied to again.  Once this happens you are running on virtual machines.... repeat this process for all your conversions and you willl have great success with your datacenter consolidations.


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‎05-17-2011 07:32 AM
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