Citrix's no-cost XenServer 5.5 compares well with VMware's ESXi. Upgrading to the Essentials or Platinum editions puts XenServer 5.5 in VMware vSphere 4 territory.
Citrix's no-cost XenServer 5.5 stacks up well compared with VMware's freely
available ESXi; adding the $2,750-per-server Enterprise edition or the $5,500
Platinum edition bumps XenServer 5.5 into vSphere 4 territory.
The Essentials pack provides high availability, dynamic workload management
and a host of other features; the Platinum edition adds a year of free upgrades
along with automated virtual lab management and physical machine load
To put the two platforms in perspective: VMware vSphere 4, released just
over two months ago, enables active virtual machines to migrate from one
physical host to another without interruption, even when those physical systems
are using different CPU models from the same manufacturer. Citrix XenServer
requires that hosts in a resource pool have the same vendor, model and
features. VMware significantly advanced virtual networking in vSphere 4 by
providing a distributed vNetwork switch. VMware also now enables third-party
switches to be integrated within vSphere 4. XenServer still provides all
networking services within its virtual infrastructure.
All that said, for data center managers with modest-sized installations and restricted
budgets, Citrix XenServer 5.5 along with the Essentials kit isn't a bad way to
XenServer 5.5 to the Test
I installed XenServer 5.5 on a Hewlett-Packard DL360 G6 and an HP DL380 G6,
as well as on a Sun Fire x4170. Each was equipped with a similar-model Xeon
5500 family processor and 12GB of RAM. The
HP DL380 and the Sun Fire x4170 had four NICs, while the HP DL360 had two NICs.
This equipment group met the basic minimums to form a XenServer resource pool.
I used OpenFiler, in the form of a Xen-compatible virtual appliance on the
Sun x4170, to create a modest-sized 500GB iSCSI shared storage repository for
the VDI (virtual disk image) files used by the virtual machines.
I was able to use the Windows-based XenCenter 5.5-the management interface
for XenServer-to integrate my resource pool with Microsoft Active Directory to
facilitate the authentication process for my XenServer administrators. It was a
straightforward process to join the AD domain. While this makes it possible to
use commonly available user provisioning tools to manage who has access to the
XenServer console, I would like to see more granular administrative controls
added to XenServer, such as those found in VMware's products. As it is, all
administrators can access any functions in XenServer.
Citrix has changed the way virtual machine backup and snapshots are
performed. It's now possible to take a snapshot from the XenCenter management
console, in addition to using the extensive CLI
(command-line interface). Snapshots are simple to kick off, requiring only a
unique name to start the process. The CLI
facilitates scripted backup and restore operations on the virtual machine
With Version 5.5, XenServer now offers support for Red Hat Enterprise Linux
5.3, Novell SUSE Linux Enterprise Server 11 and Debian Lenny. XenCenter also
now provides a view that puts resources such as physical hosts, virtual
machines, snapshots and storage repositories into folders, and resources can be
tagged to create groupings of resources for reporting purposes.
Technical Director Cameron Sturdevant can be reached at