Wednesday, December 29, 2010

Citrix Xendesktop in 2011

I think 2011 will see a tremendous amount of traction in desktop virtualization, I say desktop virtualization and not VDI because I believe to absorb truly the benefits of a virtualized desktop you need to use it as enabler to a more efficient and centralized desktop management. To achieve these goals you need to move from a monolithic design to layered approach whereby the user environment space, operating system and applications are all separated in a layered fashion. These are then dynamically delivered to the end user on demand and from any device.
Citrix have recently released Xendesktop 5 and also made fundamental changes to their supporting suite of products and how they integrate into application and desktop delivery. Here is how I see things panning out....

Hello Xendesktop 5 - Goodbye Xendesktop 4
Xendesktop 5 - Xendesktop has undertook a complete overhaul, IMA has been removed and replaced with a SQL database which also means no mixed mode farms, but greater functionality and scalability. Existing SQL management and BCR techniques must be implemented as any failure of the SQL side of things means a loss of desktop connections. Desktop Director is smart way for 1st line support guys to manage and support any Xendestop 5 VDI infrastructure.

Hello Machine Creation Services - Goodbye Citrix Provisioning Server
I have always found Provisioning services as clunky and extremely complex. The requirement for physical servers and scalability has always made me think that there has to be better way to manage images. With MCS quick deploy you simply point to a master image and the linked clones are created using an identity disk and difference disk, and the Active Directory configuration via the AD identity service. Citrix suggest you use MCS for smaller deployments and Prov Server for the larger deployments as they scale better and utilize the different write cache mechanisms. I would suggest a different approach here for two reasons.

1. The use of HSP (hybrid storage pools) and proprietary storage software that augments the current SAS/SATA storage stack and utilize SSD disks for smart disk cache; thus providing the required IOPS and performance VDI environments demand. Products such as Nexenta ZFS, FalconStor's NSS, and Disk systems from Dell and NetApp provide different features around SSD. Fusion-io's io-Drive takes a different approach and sits direct on the PCI bus and hence there is no SAS controller overhead, they OEM these to Dell and HP and the IOP'S you can pull from these devices are huge.  A typical SMB/SME environment that has a requirement for say example 500 desktops each requesting an average 10 IOPS on a 70/30 read and write ratio would require 28 SAS 15k disks to supply 5000 IOPS. This could possibly mean 4 disk shelves and the CAPEX becomes quite expensive. A hybrid SSD solution would require less hardware and are great in terms of providing the required read IOPS to cover boot storms. Something like the NexentaStor also allows the use of SSD's running on agonistic disk shelves. Although more expensive, SSD also means less disks and thus reduced CAPEX and carbon footprint.

2. Xenserver Intellicache is supported in XenServer 5.6 FP1 but not yet on Xendesktop 5. Intellicache  utilizes SSD local storage to create a smart disk read cache and uses NFS to store the gold image, the great thing about Intellicache is that it will dynamically look into desktop read patterns and cache these locally. If you were to run 100 Windows 7 desktops you will find that read patterns will be very similar, thus the net affect is fast disk access and read data deduplication. The requirement for Intellicache is MCS, so again there is no need for Provisioning server.

Hello NFS - Goodbye iSCSI and Fibre Channel
Citrix recommend Xendesktop to be run from a NFS platform; the rationale behind this is file I/O works better than block based I/O for VDI and performance. When you start to look at large amounts of desktops you can see issues with SCSI locking. I also think this is a smart move as often enterprise storage arrays are used to house virtual desktops that provide the bells and whistles of such features as synchronous replication,VSS and dual connectivity. These are not needed generally for VDI disk access, the main requirements I see are NFS, Smart caching and deduplication. High availability is a topic of discussion on VDI environments but my view is that if you take a layer cake approach and implement stateless desktops you simply need to restore the gold image and use MSC to recreate the desktops in the event of failure. NetApp and Nexenta provide some simple cost effective NFS solutions with these features.

Hello Access Gateway 5.0 VPX - Goodbye Secure Gateway
Secure remote access is critical component of any Xendesktop solution this is also driven by the consumerization of IT as we speak and varied spectrum of mobile devices. Typically in the past you either use client VPN access or a SSL VPN such as Secure gateway. Secure gateway runs on Windows and is quite limited in its functionality. With the CAG 5.0 we now have a Linux appliance that includes enterprise features such as HA, Smart Access functionality and also support for Receiver and Two factor authentication. A Xendesktop and Xenapp platform licence is included with the appliance so this is a smart and cost effective move in my opinion. This model is also crucially available as a XenServer and VMware virtual appliance, I am a great advocate of virtual appliances where possible as they bring ease of deployment, scalability and management that sits great in a datacenter infrastructure.

*Citrix have also just released Branch Repeater VPX as a VMware virtual appliance, when you need QOS, data compression, de-duplication or plan to implement soft phones and VoIP these are a great fit.

Hello Receiver and Delivery Services - Goodbye Dazzle
Dazzle is replaced by a self service plug-in in receiver and nice new ITunes like interface; this when combined with Citrix Merchandising server provides a modular and manageable delivery mechanism for applications and plug-ins. The receiver front end has a similar look and feel across all platforms so as we look into multiple device access we get a similar end user experience whether they are accessing their desktop from a Mac, IPad or Thin client. I think this makes sense when we start to look at Google Chrome OS, Nirvana Phones and Open Cloud Access which are all on the horizon.
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