CCH Company
XenDesktop 7.6 Enterprise FP1
Conceptual Design
Table of Contents
Section 1: Overview .................................................................................. 3
Executive Summary ..................................................................................................... 4
Project Overview ....................................................................................................... 4
Project Goals .......................................................................................................... 4
Section 2: Conceptual Design .................................................................. 5
Architecture .................................................................................................................. 5
Design Considerations ................................................................................................. 6
User Layer ................................................................................................................. 6
Access Layer ............................................................................................................. 6
Resource Layer ......................................................................................................... 6
Personalization ....................................................................................................... 6
Virtual Desktops & Applications.............................................................................. 7
Control Layer ............................................................................................................. 7
Databases .............................................................................................................. 7
Virtual Machine Management ................................................................................. 7
Image Management ............................................................................................... 8
Hardware Layer ......................................................................................................... 8
Resource Hosts ...................................................................................................... 8
SECTION 1: OVERVIEW
Executive Summary
Project Overview
CCH Company is in the process of designing a new XenDesktop Enterprise 7.6 FP1 environment that
will provide virtual desktops and applications to their worldwide user base. CCH Company envisions
an environment that can provide users with a completely virtual workspace, allowing them to work
from anywhere. CCH Company has worked with their internal virtualization architect and a third party
consulting team to design a solution that is scalable to ten-thousand users and fully active across two
datacenters.
The Conceptual Design provides a high-level overview of the proposed Citrix solution, including Citrix
components required, sizing estimates and design considerations for each architectural layer. The
next step of the design phase will be to engage a Citrix consultant to assess this design for potential
design risks and to provide detailed recommendations on how to improve the current design, as well
as ensure the design properly addresses CCH Company’s requirements.
Project Goals
During the course of the project, CCH Company identified a number of different project goals. The
following table summarizes those goals and illustrates how this Conceptual Design deliverable
addresses them.
Priority
Key Initiatives
Description
1
Multi-Datacenter Design
CCH Company would like to design a fully active/active
XenDesktop environment that spans across two datacenters.
The design should be configured for user data and profiles to
be fully replicated with a failover time of less than five minutes.
The datacenters are connected via 1Gbps fiber links and are
treated as a single entity allowing a single XenDesktop site to
be deployed.
2
Single Access URL
To allow for seamless access into the Citrix environment, CCH
Company would like to have a single URL that works internally
and externally. Previous consultants stated that having a single
URL to access Citrix was unsupported and CCH Company
would like to inquire if this limitation still exists and how to work
around it.
3
Secure Remote Access
CCH Company has a requirement for seamless secure remote
across into the new Citrix environment for employees that work
from home along with third-party contractors. CCH Company
currently uses VPN software to gain access into the current
internal Citrix resources.
4
Single Image Management
The current Citrix XenApp deployment does not leverage any
single image management solution to ensure consistency and
reduce administrative overhead. For the new XenDesktop
deployment that includes both desktops and applications, CCH
Company would like to leverage Machine Creation Services
from Citrix to increase operational efficiently when deploying
resources.
5
Accurate Hardware Sizing
CCH Company’s budget planning process requires that
accurate hardware sizing for the coming XenDesktop
deployment be completed. Based on the proposed user
requirements, single-server sizing should be recommended that
provides optimal user performance while maximizing the
investment of the server hardware.
SECTION 2: CONCEPTUAL
DESIGN
Architecture
The following diagram shows the conceptual architecture for the CCH Company datacenters.
CCH Company’s forthcoming XenDesktop 7.6 FP1 deployment will be located in two datacenters: Los
Angeles, CA and Atlanta, GA. These datacenters will support an active/active Citrix deployment that
allows users to access the datacenter closest to them. Approximately 10,000 users will be split between
the two datacenters based on their location. Although users will be split between locations, each
datacenter must be capable of supporting the full user load in the event of a failure in one location. Due to
the importance of the applications accessed, the deployment must be designed for a fully automated
failover than occurs in less than five minutes in the event that a single datacenter becomes unavailable.
A single XenDesktop site spanning both datacenters will be created. Creating a single site allows both
datacenters to be managed as a single entity form the same console. CCH Company’s datacenters are
connected via multiple 1 Gbps lines, so they are treated as a single datacenter.
CCH Company will provide Windows 8.1 virtual desktops along with XenApp hosted published
applications. To reduce management overhead, CCH Company will use Machine Creation Services to
allow for single image management of desktops and application servers. A mix of pooled and persistent
desktops will be provisioned to end users. Persistent desktops will be made available to the entire IT
department, which includes developers that require the ability to install their own software. All other user
groups will use pooled desktops.
Design Considerations
User Layer
i
The User Layer focuses on the unique qualities of each user group such as their network connectivity to the
datacenter, endpoint devices, or other unique requirements.
Most of the end users at CCH Company will be working from the corporate headquarters in Los
Angeles. Users will be accessing the environment from several different devices such as thin clients,
mobile devices (iPad), laptops, and full desktops. An initiative has been set in motion to virtualize all
endpoint devices in the office. This will allow all the data and applications to be centralized in the
datacenter rather than having thick clients.
Access Layer
i
The Access Layer focuses on the method and process users follow in order to establish and maintain a
connection to their resources.
Internal users will gain access to applications and desktops by connecting to one of two StoreFront
servers located in each datacenter. Since the NetScaler appliance is located in the DMZ to provide
remote access, the security team has mandated NetScaler not be used to load balance internal
resources such as StoreFront. Instead, StoreFront high availability will be provided using DNS Round
robin. This will ensure employees will always be able to access StoreFront in the event of a failure. To
provide a consistent user experience, applications that users subscribe to should appear on the
StoreFront servers in both locations.
External users will access the environment by connecting through NetScaler Gateway. A set of two
NetScalers will be located in each datacenter to provide this functionality. To provide redundancy and
optimal performance, the NetScalers should be able to provide load balancing and failover between
datacenters.
Resource Layer
i
The Resource Layer of a solution focuses on personalization, applications, and image design. The Resource
Layer is where users will interact with desktops and applications and is most visible to the end users.
Personalization
To provide personalization inside virtual desktops and applications, Citrix Profile Management and
Microsoft folder redirection will be used. To allow users to access their data irrespective of what
datacenter they connect to, profiles and user data will been configured to actively replicate between
datacenters using DFS-R. This will ensure that data is constantly synced between both locations.
Virtual Desktops & Applications
CCH Company will be delivering Windows 8.1 virtual desktops to their end users via XenDesktop.
Applications should be made available seamlessly inside the XenDesktop session and appear as
though they are locally installed applications. Desktops will be deployed using Machine Creation
Services using two Windows 8.1 golden images. One image will be used for the Pooled desktops and
the other will be used for the dedicated desktops. Pooled Desktops will be provide to a majority of the
user base including sales, marketing, and finance groups. Dedicated desktops will be provided for the
IT department which includes support staff, developers, and managers. Due to the importance of the
dedicated desktop users, the desktops must be able to be highly available between the Los Angeles
and Atlanta datacenters.
Application servers will also be deployed using Machine Creation Services using three Windows 2012
golden images. To improve performance, CCH Company would like to leverage the XenServer cache
in memory feature Citrix provides in order to reduce writes and reads to the storage array. Below is a
table with a list of the server images and the applications installed on them:
Image
Application Notes
General Apps
This image includes general applications include the Office suite and Internet
Explorer.
My CRM
The primary CRM application used throughout the company. Requires a
backend FoxPro database that is unable to be actively replicated between
datacenters.
Total Accounting
The software package used by the accounting department. It requires a
Microsoft SQL backend database that currently is only located in the Los
Angeles datacenter.
To provide high availability between the resource and the control layers, Citrix NetScaler will be used.
The NetScaler will load balance the communication and registration process between the Virtual
Desktop Agent (VDA) software installed on the desktops/application servers and the Delivery
Controllers. If communication is lost between the two layers, users will be unable to access their
resources.
Control Layer
i
The Control Layer includes all infrastructure related components supporting the overall solution. This includes
the Citrix controllers, image management through MCS or PVS, and the creation and publication of hosted
resources.
Databases
The proposed design will use a single SQL database located on the existing SQL server
infrastructure. The existing SQL infrastructure is configured in three-node mirrored configuration
with a primary, secondary, and witness server.
Virtual Machine Management
The Citrix XenServer pool master role will facilitate communication between the XenDesktop
Delivery Controllers and the Desktop-Based OS and Server-Based OS resource pools. If the
XenServer pool master is unavailable, a replacement server will be promoted from the relevant
resource pool.
Image Management
Machine Creation Services (MCS) will be used to deploy the pooled desktop and application server
images. MCS allows virtual machines to be provisioned and re-provisioned in real-time from a
single shared-disk image. In doing so, administrators can eliminate the need to manage and patch
a large majority of the virtual machines. Citrix Machine Creation Services does not require
additional hardware or resources as it simply utilizes the hypervisor and storage subsystem to
create unique, thin provisioned clones of the “gold image”, resulting in a solution that is simple to
deploy and easy to scale. The dedicated desktops will still have to be maintained manually using
another software product.
Hardware Layer
i
The Hardware Layer is responsible for the physical devices required to support the entire solution including
servers, and storage devices.
Resource Hosts
Within the Hardware Layer, Resource Hosts are responsible for hosting the desktops and
application servers. The design decisions of hardware type, hypervisor and storage type directly
impacts the number of servers required.
The different workload types (server and desktop) should each be placed on separate physical
servers. This is due to differences in the workloads and the CPU overcommit ratio that acceptable
for each type of workload. To improve efficiency, CCH Company has requested the design
maximize the investment on hardware while providing the best performance.
The single-server resource calculations for the XenApp application servers running on Windows
2012 are as follows:
Category
Design Decision
Notes
Server CPU
4 Sockets X 12 Cores =
48 Physical Cores Available
Although Hyper threading is
enabled, only Physical cores will
be used in the calculation
# of VMs per Host
15 Virtual Machines X 4 vCPU =
60 vCPU allocated per Physical Host
This will allow the server
resources to be maximized for
investment
Overcommit Ratio
60 vCPU / 48 Physical Cores =
1.25 CPU Overcommit Ratio
RAM Allocation
512 GB total server memory –
30 GB for MCS Read Cache (3 Images *
10 GB Average Size) –
2 GB for Hypervisor
= 480 GB / 15 VMs = ~ 32 GB per VM
Storage
50 GB Master Image (10 GB used)
IOPS (Steady State)
60 Per App Server
The number of storage IOPS
estimated for the application
servers is derived from testing
using average medium user
workload. The IOPS estimate is
an average of the steady state
and is not a peak average.
The single-server resource calculations for the XenDesktop virtual desktops running on Windows
8.1 are as follows:
Category
Design Decision
Notes
Server CPU
4 Sockets X 12 Cores =
48 Physical Cores Available
Although Hyper threading is
enabled, only Physical cores will
be used in the calculation
# of VMs per Host
150 Virtual Machines X 2 vCPU =
300 vCPU allocated per Physical Host
This will allow the server
resources to be maximized for
investment
Overcommit Ratio
300 vCPU / 48 Physical Cores =
6.25 CPU Overcommit Ratio
RAM Allocation
512 GB total server memory –
15 GB for MCS Read Cache –
2 GB for Hypervisor
= 495 GB / 150 VMs = ~ 3.3 GB per VM
Storage
40 GB Master Image (15 GB used)
IOPS (Steady State)
30 Per Desktop
The number of storage IOPS
estimated for the desktops is
derived from testing using
average medium user workload.
The IOPS estimate is an average
of the steady state and is not a
peak average.
Will utilize local storage rather than shared storage to reduce costs and spread the load. Each
server is configured with four 250GB SSD drives in a RAID 5 array. A total of 1.5 TB of usable
space is available
Category
Design Decision
Notes
# of Drives
4
The servers fit a maximum of four drives.
Drive Size
250 GB
The size of the SSD drives purchased.
RAID Level
RAID 10
Chosen for its speed and reliability features.
Usable Space
464 GB
The amount of usable space after the drives
are configured in RAID 10.
Desktop Differencing
Disk Size
1 GB
The differencing disk should only grow to
about 1 GB in size. User data will be stored on
a network drive so very little data will be
written to the desktop.
Application Server
Differencing Disk Size
25 GB
The differencing disk should only grow to
about 10 GB in size. Between user profile data
that is temporary downloaded and Windows
temp files, no other data should be written to
this disk.