Citrix XenServer vs VMware VSphere

Citrix XenServer vs VMware VSphere


Last updated August 11, 2017


When assessing the pros and cons of Citrix XenServer Vs VMware vSphere ESXi, it should be noted that these two software systems are developed and supported by different companies. The VMware vSphere ESXi is developed by VMware Inc, whereas XenServer is developed by Citrix.

Though they perform similar roles, they do have a few distinct differences which make them unique.
The main difference between the two is the intended usage of the software. The Citrix XenServer is used by personal users and small to medium sized businesses while VMware vSphere ESXi is only intended for small to medium sized businesses and is not structured for personal use. 

Technical Specifications:

Both of these software programs run the Bare Metal (Type 1) hypervisor type and support the x86 and x64 architecture. Though they support various types of virtualization such as hardware assisted virtualization and para-virtualization, only VMware vSphere ESXi does support full virtualization. Neither of the two support operating system virtualization. Here's the article on VMware vSphere Best Practices
Both these softwares support a variety of storage options. The difference between them, when it comes to virtualization, is that VMware does support FCoE and SSD for Swap and does not support USB, SATA, SAS, NFS, iSCSI which are all supported by Citrix XenServer. Both of them support DAS, FC and NAS storage while neither of them support eSATA and RDM. Both systems have also gained lots of users in the education, financial services, healthcare, and the government.

[Related read: What are the main advantages of Citrix XenServer?]


The Citrix XenServer and VMware vSphere ESXi pricing comparison offers a few interesting insights into the different business models that they have adopted. XenServer is open source and free and does provide per server licensing. VMware, on the other hand, demands a proprietary license and is licensed per processor. Both products do have a substantial client following dotted all over the globe irrespective of their pricing structure.

Virtual Machine Limits:

Both these software programs have a virtual disk size of 2000GB, but the RAM per virtual machine does vary with the VMware, since it offers a staggering 1024 GB while the Citrix XenServer offers 128GB per virtual machine.
The XenServer has a total of sixteen (16) Virtual CPUs per Virtual Machine (VCPUS) and the VMware has double this, at thirty two (32) VCPUS. The XenServer provides a total of 7 Virtual Network Interface Cards (NICs) per virtual machine and sixteen (16) Virtual Disks per Virtual machine. On the other hand, VMware vSphere ESXi  has a total of ten (10) virtual Network interface cards (NICs) per virtual machine and a whopping sixty two (62) virtual disks per virtual machine.

Virtual Network Interface – VMware vSphere

Virtual Network Interface – VMware vSphere

Virtual Network Interface – Citrix XenServer

Virtual Network Interface – Citrix XenServer


Host Server Limits:

  • VMware vSphere has a total of 120 (hundred and twenty) virtual machines per host with the RAM per host being at 2048 GB with a total of 2048 virtual disks per host.
  • XenServer has a total pack of 75 (seventy five) virtual machines per host with a RAM of 1024GB per host and 512 virtual disks per host.
  • Both systems have 160 (hundred and sixty) logical CPUs per host with the VMware capable of having a total of 2048 Virtual CPUs per host. However, XenServer does not have any virtual CPUs on the host. 

Virtualization Management features:

One area where these programs tend to differ and to a large extent can explain the disparity in acceptance and usage levels between the two is virtualization management.
  • The only key management feature that is supported by both software programs is Thin Provisioning.
  • While VMware does not support Asset Management and Configuration Mapping, XenServer does support these two management features in addition to Thin Provisioning but does not support key features such as Dynamic Resource Allocation, Failover and Live Migration. These three important features are on the other hand fully supported by VMware vSphere ESXi.
  • It should be noted though that if you are looking for other additional features such as Automated Workflows, High Availability (HA), Maintenance Mode, Shared Resource Pools and VM Backup / Restore then it is advisable to try out other software programs such as VMware vSphere Essentials.

Supported Host Operating Systems:

The next area that differentiates the two is supported host operating systems, which is without doubt the Achilles heel of VMware vSphere is the number of host operating systems supported by the program.
  • VMware vSphere does only support MS DOS and Free BSD as hosts.
  • On the other hand, Citrix XenServer does support a plethora of host operating systems such as Novell Linux Desktop, Red Hat Enterprise Linux AS, Linux ES, Linux WS and Red Hat Linux. Other OS supported include Windows 2000 Professional and Server, Windows 98 and 95, Windows Me, Windows NT Server, Windows NT Terminal Server, Windows NT Workstation, Windows Server 2003 Enterprise, Web and Standard Editions and Windows XP Home and Professional editions.

Supported Guest Operating Systems:

On this front, the Citrix XenServer vs. VMware vSphere ESXi battle is relatively even as they both do support the following guest operating systems; Novell Linux Desktop, Red Hat Enterprise Linux AS, Red Hat Linux ES, Red Hat Linux WS ,Red Hat Linux, Windows 2000 Professional , Windows 2000 Server, Windows 98 , Windows 95, Windows Me, Windows NT Server, Windows NT Terminal Server, Windows NT Workstation, Windows Server 2003 Enterprise, Windows 2003 Web , Windows 2003 Standard, Windows XP Professional and Windows XP Home edition.

The exception however is that VMware does support MS DOS, Sun Java Desktop System and Solaris x86 platform edition as guest operating system while Citrix XenServer does not support any of the above mentioned three operating systems either as host or guest operating systems. 

Technical Support:

Both these softwares support a variety of technical support media such as forums, instructional videos, online self-service, knowledge base, system upgrades, telephone, and white papers.

They also differ in this area as VMware does not provide technical support via blogs, brochures, email and owner’s manual but most importantly does have a well manned help desk and also offers a remote training option. Citrix XenServer on the other hand does provide technical support through blogs, email, brochures, and user’s/owner’s manual but does not provide this support through a help desk or through remote training.

Market Recognition:

Coming to market presence and recognition space, the VMware vSphere ESXi seems to be head over shoulders with its competitor. For instance, just a few months ago the Top 50 Most Influential channel chiefs in the 2014 Virtualization Review gave VMware Horizon View the 2014 reader’s choice award in the VDI and Desktop Virtualization category. Additionally, backing it up are leading companies like Ducati, Revlon, and NYSE Euronext.

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About the Author

Founded in 2009, Simplilearn is one of the world’s leading providers of online training for Digital Marketing, Cloud Computing, Project Management, Data Science, IT, Software Development, and many other emerging technologies. Based in San Francisco, California, and Bangalore, India, Simplilearn has helped more than 500,000 students, professionals and companies across 200 countries get trained, upskilled, and acquire certifications.


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