How to Hot Add CPU and RAM with VMware vSphere

One of the many benefits of using virtual servers over physical servers is the ability to add server resources such as CPU, RAM, and disk space on the fly without downtime. An addition drawback with a physical server is that you were often limited by the physical capacity of the server.  Once those limits were reached the server couldn’t be upgraded further.  Adding resources also required powering off the server which in turn would require coordinating with business owners and impacted users. Not all editions of Windows support hot-add so be sure to confirm your server is supported before starting. In this walkthrough I’ll show how easy it is to add server resources using VMware’s vSphere client.\r\n

Logging into vSphere Client

\r\nAfter authenticating on my network with the VMware vSphere 5.5 client I go to Hosts and Clusters under Inventory. From here I have access to all the virtual servers configured in our environment. After selecting the server to be upgraded you will be see the Getting Started tab. From here you have access to the usual administrative tasks such as starting, stopping, and restarting the server as well as performance reporting and events about the server. Click Edit virtual machine settings to add resources.\r\n\r\nCapture2\r\n\r\n \r\n

Enabling RAM and CPU Hotplug

\r\nAdding the additional resources is straight forward. However when you begin you may find the CPU and Memory properties disabled. This indicates that the server has not been been previously enabled for hot adding resources. In this instance the server will need to be shutdown before you can upgrade these resources.\r\n\r\nCapture3\r\n\r\n \r\n\r\nFortunately fixing this for future upgrades is a simple matter. When the server is powered down click on the Options tab of the Virtual Machine Properties. Under the Advanced settings go to the Memory/CPU Hotplug properties. Click Enable memory hot add and Enable CPU hot add. Click OK to save the changes. After the server is powered back on you will now be able to add CPU and Memory without having to first shutdown the server.\r\n\r\n \r\n\r\nUntitled-1\r\n\r\n \r\n\r\nTo add additional virtual CPUs simply increase the Number of virtual sockets and click OK to save the changes.\r\n\r\ncore\r\n\r\n \r\n\r\nTo add additional Memory to the server adjust the Memory Configuration accordingly and click OK to save.\r\n\r\nUntitled-2\r\n\r\n \r\n\r\n \r\n

Adding Additional Disk Space

\r\nIn addition to adding CPU and Memory to the server during this maintenance window I am also going to add disk space. Adding additional disk space is just as straight forward as adding CPU and Memory. In the Virtual Machine Properties on the Hardware tab go to the Hard disk settings. Increase the Provisioned Size by the new amount and click OK to save the changes. Windows will not automatically recognize the new space so the final step of the upgrade will be log into the server and Extend the server’s disk drive. This can either be accomplished using vShere’s server console window or by connecting to the server with Remote Desktop.\r\n\r\nCapture5\r\n\r\n \r\n

Extending Windows Disk Space

\r\nAfter logging into Windows open the Computer Management snap-in. In the console tree click on Disk Management under Storage. You may need to Rescan the disk before Windows will see that the new space is available.\r\n\r\nCapture6\r\n\r\n \r\n\r\nStep through the Extend Volume Wizard to allocate the additional space on the existing volume.\r\n\r\nCapture7\r\n\r\n \r\n

In Summary

\r\nVMware vSphere offers System Administrators complete control over virtual server properties. Adding additional CPU, RAM, and disk space is  straight forward and in many cases can be performed without having to shutdown the server.  To help minimize downtime of your next maintenance window, double check the edition of your Windows server supports hot-add and confirm the Memory/CPU Hotplug property has been enabled. Thanks for reading.

Peter Viola

Creative, customer focused, results oriented, Senior Web Systems Engineer who enjoys providing the highest level of customer service supporting complex Windows hosting solutions. MCITP, MCSA, MCTS

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