Lets refresh where we are! We are discussing about architecting a Citrix environment from Architects perspective. There are 2 parts to it:
1) Assessment
2) Design
Assessment is further divided into
· Infrastructure
· Security and personalization
· Operation and Support
· Conceptual Architecture
In this blog, we will discuss assessment of Infrastructure. Each topic will be covered in separate blog.
The existing infrastructure has a
major impact on the final solution. Depending on the environment or
organization, some functional areas can be altered, but other areas cannot.
Architects must understand the limitations of the current environment so that
they can plan accordingly.
Network Architecture
Assessing the network architecture
is an important piece of the infrastructure assessment.
Architects should ask the following
questions:
- Can the organization's LAN support existing usage?
- Are there any WAN optimization upgrades planned in the
near future?
- Who are the technical contacts for the network
environment?
- Which network connection types exist?
- How many router hops exist between the user and the Web
Interface?
- How much network traffic, including traffic from file,
print, Web and XenApp servers, do the servers typically handle?
- Are there any network management tools in place? If so,
which are they?
- Do firewalls exist between the development, test and
production environments?
Answers to these questions help the
architect gain an understanding of the network environment, which will help
with creating the infrastructure design. Architects can also use metrics to
gather network data.
Additional Network Architecture
Topics
Additional topics related to network
architecture that should be reviewed during the assessment include the
following:
- WINS and DNS name resolution
- Switch port configuration (hard-coded or
auto-negotiated?)
- Latency
- Available bandwidth
- WAN circuits
- Quality of service
Network Architecture Risks and
Recommendations
|
Risk
|
Recommendation
|
|
NIC teaming is not implemented for
critical servers.
|
Implement NIC teaming to eliminate
single points of failure.
|
|
NICs are not manually configured
for speed.
|
Do not auto-configure NICs.
|
|
Quality of Service is not
configured on ICA traffic.
|
Configure QoS if necessary,
especially if mission-critical applications are running on ICA.
|
Windows Server and Active Directory
Windows Server and Active Directory
are reviewed during most assessments in an enterprise environment. During this
section of the assessment, an architect reviews the following items:
- Operating system configuration
·
- Which operating systems are used?
- Which service packs are installed?
- Active Directory structure
- How are desktops organized within Active Directory?
Some
organizations may be using Novell Directory Services instead of Active
Directory.
- How are servers organized with Active Directory?
- Group Policy Objects
- Which GPOs are set?
- Which policies exist?
- Are local security policies or AD-based GPOs used?
- Logon scripts
- Are scripts used?
- What drives the need to use logon scripts, if
applicable?
- What are the logon settings?
- How is the pagefile configured?
- User profiles
- Which type of profiles are used?
- Where are the profiles stored?
- User file storage
- Where do users store their data?
- Are folders being redirected?
Active Directory
Active Directory (AD) and the
structure of items such as organizational units (OUs) and groups are an
essential part of personalization in a virtualization environment. Placing
virtual desktops and servers into their own OU is a best practice. OUs
facilitate easier deployment of Group Policy Objects (GPOs) throughout the
domain. Architects should ask the following questions:
- What is the Active Directory functional level?
(Example: 2003 or 2003/2008 mixed)
- What is the configuration of domain membership?
- What are the details for user group membership?
General Active Directory
recommendations include the following:
- Create specific AD groups for each application, which
makes Active Directory easier to manage.
- Nest local AD groups inside domain AD groups.
Enterprise Storage
Storage has a direct impact on the
speed and performance of the environment. Enterprise storage should be robust
and easily accessible, in order to not impede users or the storing of data.
Actual usage of storage space depends heavily on the usage patterns of the user
and length of time that desktops are in use.
In most Citrix environments,
enterprise storage is stored on SAN or NAS devices. During an assessment, an
architect may use an automated tool to gather data about available storage,
followed by a conversation with the Storage Administrator for the organization.
The architect typically assesses the storage solution, storage types utilized
by an organization, application and database usage and any details about
storage related to desktop delivery.
In review meetings, storage assessment
leads into a conversation about networking. Questions to ask about storage
during the infrastructure assessment include the following:
- Are there any policies around the allocation of SAN
resources?
- How is storage configured on the SAN, if applicable?
Which type of hardware is being used?
- Who is responsible for modifying the LUN and SAN
switching configurations?
- Is your SQL cluster on shared storage?
Databases
should be on shared storage, as a best practice.
- If a file server is used, is it clustered? Clustering
file servers is a best practice.
- If a SAN is implemented, which type of SAN?
Storage Recommendations and
Considerations
The following recommendations and
considerations are also important for assessing enterprise storage:
- If XenDesktop and Provisioning Services will be
configured, a NAS Gateway or a third-party program is required to control
the reads and writes to the LUN on the SAN. Provisioning Services requires
file-based storage in this situation.
- Ensure that the HA configuration on Provisioning
Services is set to active/active. The SAN can become corrupted if not
configured correctly.
From
the Architect
Storage and storage requirements
should be allocated to the storage team. It is very important to remember that,
for virtualization projects, legacy sizing and storage often no longer meet the
requirements of a virtualization environment. Because sizing and storage will
likely be revamped during the design, focusing on storage considerations early
on saves time later
Backend Data
Users access backend data for many
applications. Assessing the databases and other resources provided for user
access is an important part of the assessment. Because some users may not
understand the interaction between the program on the desktop and the backend
data, users may perceive issues in one area that are caused in another area.
As an example, if a user accesses
e-mail and perceives it as slow, the issue might be related to the backend mail
system, the network or the desktop. From the user's perspective, the source of
the issue is unknown. When that user reports the issue to the help desk, it is
unlikely that the backend data source will be identified as the problem.
Questions architects typically ask
when assessing backend data include:
- Where is the data store located?
It is a
common best practice to ensure that databases are logically near to the Citrix
infrastructure and applications.
- Where are the application servers located?
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