There are many similarities with managing storage in a Citrix environment compared with a Hyper-V or VMware environment. For instance, all three environments have similar functionality, such as raw device mapping (RDM) and the ability to write to a file on a dedicated file system. With the Citrix XenServer environment’s management platform, a storage administrator can access any given storage device, set up new NFS-based storage through a wizard-like interface and more.
In this podcast interview, Sander van Vugt, Linux high availability and virtualization expert, discusses best practices for storage in a Citrix environment. Discover the differences between the Citrix XenServer, vSphere and Hyper-V platforms; what tools Citrix and third-party vendors provide to ease XenServer storage management; and how to enhance storage performance in a Citrix virtual server environment. Listen to the podcast or read his answers below.
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SearchVirtualStorage.com: How is managing storage for a Citrix XenServer virtual server environment different from managing storage for a VMware or Hyper-V environment?
Van Vugt: Basically, it’s not that different. Storage is based on the same principles on all three environments. So in VMware you have raw device mapping, and in Citrix and Hyper-V, there are similar solutions. Likewise, they can all write the storage to a file on the dedicated file system if you don’t have to write directly to the storage. The main difference between … them is in the management interface that XenCenter provides for storage management, so the interface gives easy access to the storage device of choice, and that seems to be different in all the solutions.
SearchVirtualStorage.com: Tell us about that XenCenter interface. How does it work?
Van Vugt: [With that management interface], different storage options are set up through an easy wizard-like interface and allow customers to set up NFS-based storage or connect to a storage repository on software, iSCSI or a hardware HBA.
It’s also easy to connect to ISO libraries using NFS or CIFS protocols. And apart from that, Citrix offers advanced StorageLink technology as an add-on. So this solution is developed to integrate with storage that is provided by third-party vendors. One benefit of the solution is that it provides a generic interface that allows users to manage different SAN fabrics and arrays. So that means that you can manage interfaces from one Citrix environment but not necessarily from the SAN fabric environment.
Also, because it integrates so well with these storage solutions, storage [managers] can take advantage of features by device, such as thin provisioning, fast clones, fast snapshots and all those kinds of pieces that make storage really nice to work with and which aren’t necessarily known to the native Citrix environments.
A third benefit is that StorageLink allows administrators to set apart their storage profiles
for new virtual machines (VMs). These storage profiles can then be linked to storage volumes in
SearchVirtualStorage.com: What third-party tools are available to help IT shops manage storage to support their Citrix environments?
Van Vugt: What you’re looking at is mainly hardware-specific versions of XenServer. For instance, XenServer Dell Edition is optimized to run from flash storage in Dell servers, and in such environments the XenServer EqualLogic storage data can be used to allow thin volumes to be created from a XenCenter interface. So we’re not really looking at generic tools, but more at specific tools that allow you to integrate specific kinds of storage devices in virtualization environments.
SearchVirtualStorage.com: Finally, what techniques can IT shops use to fine-tune performance of storage in a Citrix environment?
Van Vugt: First, they need to choose the right kind of storage for the solution they want to implement. If, for example, ultimate speed is needed, they are better off connecting directly to a LUN instead of creating a file on a file system. The next step, after you have chosen the right tool, is to choose the right hardware, because there are so many differences in hardware. Specialized solutions for storage optimization exist on the market, like Atlantis for Citrix XenServer. This is a software appliance that runs on top of the XenServer hypervisor to optimize access for mainly the XenDesktop Virtual Desktop. But these kinds of storage optimization solutions are used to optimize the storage process for a VDI environment and not necessarily for a virtualized server environment. So for server environments, it’s a different story. An optimization takes place on the SAN fabric itself, mostly.
This was first published in February 2012