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  • Дата регистрации: 05.06.2004
  • ФИО: Лена
  • День рождения: 5.10.1977
  • Пол: женский
  • Регион проживания: Россия, Московская область, Москва
  • Образование: высшее техническое

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Building a Service Level Agreement
in the Data Center
As we discussed in the Service Level Management in the Data Center article, the ability
to deliver according to pre-defined agreements increasingly becomes a competitive
requirement. Aside from being able to deliver highly available, reliably performing
systems, just being able to deliver your promise is key to success. This is why an
effective and efficient Service Level Management (SLM) system is important. Key to
the success of such a system is a sound Service Level Agreement (SLA).
This article describes what role an SLA plays in the Internet Data Center (IDC) and
how it helps assure that one’s reputation stays intact. It also includes sample
agreements that can be used as templates.
Due to time sensitivity, the necessary localization and customization legal aspects
are not included in this article.
Service Level Agreements
A good SLA helps the IDC promise what is possible to deliver and deliver what is
promised.
In this article, we will establish what an SLA is and provide two sample agreements
and one example of how an agreement can map to key performance indicators. A
section on why we believe SLAs are so important and what we believe are the
essential benefits of managing against one follows these sections.
2 Building a Service Level Agreement in the Data Center • April 2002
What a Service Level Agreement Is
An SLA sets the expectations between the consumer and provider. It helps define the
relationship between the two parties. It is the cornerstone of how the service
provider sets and maintains commitments to the service consumer.
A good SLA addresses five key aspects:
n What the provider is promising.
n How the provider will deliver on those promises.
n Who will measure delivery, and how.
n What happens if the provider fails to deliver as promised.
n How the SLA will change over time.
In the definition of an SLA, realistic and measurable commitments are important.
Performing as promised is important, but swift and well communicated resolution
of issues is even more important.
The challenge for a new service and its associated SLA is that there is a direct
relationship between the architecture and what the maximum levels of availability
are. Thus, an SLA cannot be created in a vacuum. An SLA must be defined with the
infrastructure in mind.
An exponential relationship exists between the levels of availability and the related
cost. Some customers need higher levels of availability and are willing to pay more.
Therefore, having different SLAs with different associated costs is a common
approach.
The following section contains an example template of an SLA to show all of the
important components one wants to address in such a document.
The SLA example in TABLE 1 is based on the short form template that is available
from nextslm.org (http://www.nextslm.org/). An online learning community,
nextslm.org is dedicated to providing clear, concise answers about SLA. They are
sponsored by BMC, PriceWaterhouseCoopers and Sun Microsystems, Inc.
This template is customized and augmented to reflect a service provider model. By
replacing the italicized text with specific service aspects the template can be
customized to reflect a specific service offer.
Service Level Agreements 3
TABLE 2 shows the number of violations and associated penalty on a monthly basis.
TABLE 1 SLA Template
The insert service name is used by insert customer name to insert description of
the service capability. The Internet Service Provider (ISP) guarantees that:
The service name will be available insert percentage of the time from insert normal hours
of operation including hours and days of the week. Any individual outage in excess of
insert time period or sum of outages exceeding insert time period per month will
constitute a violation.
Insert percentage of service name transactions will exhibit insert value seconds or less
response time, defined as the interval from the time the user sends a transaction to
the time a visual confirmation of transaction completion is received. Missing the
metric for business transactions measured over any business week will constitute a
violation.
The IDC Customer Care team will respond to service incidents that affect multiple
users (typically more than 10) within insert time period, resolve the problem within
insert time period, and update status every insert time period. Missing any of these
metrics on an incident will constitute a violation.
The IDC Customer Care team will respond to service incidents that affect individual
users within insert time period, resolve the problem within insert time period, and
update status every insert time period. Missing any of these metrics on an incident will
constitute a violation.
The IDC Customer Care team will respond to non-critical inquiries within insert time
period, deliver an answer within insert time period, and update status every insert time
period. Missing any of these metrics on an incident will constitute a violation. A noncritical
inquiry is defined as a request for information that has no impact on the
service quality if not answered or acted upon promptly.
The external availability measurements are done by insert test company name and
reported on a monthly basis to insert customer name. The internal processes are
measured and reported by the ISP to the insert customer name on a monthly basis. This
service includes incident reporting.
TABLE 2 Monthly Violations and Associated Penalties
Number of violations Penalty
1>5 Insert penalty. Typically a reduction in fees.
5>10 Insert penalty. Typically a reduction in fees plus some additional
compensation and a corrective action plan.
10> Insert penalty. Typically a reduction in fees plus some additional
compensation and a corrective action plan.
4 Building a Service Level Agreement in the Data Center • April 2002
As services and technologies change, the SLA may change to reflect the
improvements and/or changes. This SLA will be reviewed every six months and
updated as necessary. When updates are deemed necessary, the customer will be
asked to review and approve the changes.
Other areas that must be defined in an SLA are details on how the measurements are
done, what usage limitation the service has with regard to number of concurrent
users and so forth, and details on how and who receives reports and how conflicts
are arbitrated. Because these topics are unique in each contract, they are not
included in the preceding example.
This SLA is a “short form” SLA to illustrate essential aspects between a consumer
and provider in an ASP context. Internal SLAs, between operations support groups
in the IDC, for example, are different and often contain more details and
specifications.
The main reason for this difference is that internal SLAs are driven by budget
constraints and the business management’s view of IT, while external SLAs are
driven by revenue, cost and earnings.
The following template provides a general description of an internal SLA as well as
the owners approval and review process, and a definition of the terms used in the
document. It is another example of an internal SLA from nextslm.org.
TABLE 3 Internal SLA Template
1.0 Statement of Intent This section states the objectives of the document.
1.1 Approvals All parties must agree on the SLA. This section
contains a list of who approved the SLA.
1.2 Review Dates This section contains the track record of the SLA
reviews.
1.3 Time and Percent Conventions This section contains the descriptions of what time
conventions and metrics are being used.
2.0 About the Service This section introduces the service addressed by this
SLA.
2.1 Description This section describes the service in detail.
2.2 User Environment This section describes the architecture and technologies
that are used by the consumers of the service.
3.0 About Service Availability This section introduces the availability concepts used
in this SLA.
3.1 Normal Service Availability
Schedule
This section describes what is considered normal
service availability.
3.2 Scheduled Events That Impact
Service Availability
This section describes what scheduled outages are to
be expected,
Service Level Agreements 5
How an SLA Maps to Key Performance Indicators
TABLE 4 uses the first example SLA and shows, in the right column, what key
performance indicators result from the stated commitment. These indicators. in turn,
drive what performance data and metrics are collected by the SLM process. A
separate article regarding SLM describes how this information interacts with the
SLM system. The performance indicators in TABLE 4 drive the internal SLAs and
their associated metrics.
FIGURE 1 shows how different internal groups (networking, systems and
applications) must commit to certain transaction response times to achieve the
promised levels of service to the consumer.
3.3 Non-emergency Enhancements This section describes the process that inserts
enhancements into the infrastructure.
3.4 Change Process This section describes the complete process of how
changes are introduced in the service., including the
associated availability impact.
3.5 Requests for New Users This section describes the provisioning process of new
users/customers.
4.0 About Service Measures This section contains a detailed description of how the
service availability is measured and reported.
TABLE 3 Internal SLA Template (Continued)
6 Building a Service Level Agreement in the Data Center • April 2002
TABLE 4 SLA Key Performance Indicators
Commitment Key Performance Indicator
The service name will be available insert
percentage of the time from insert normal hours of
operation including hours and days of the week.
Any individual outage in excess of insert time
period or sum of outages exceeding insert time
period per month constitutes a violation.
Service Availability as a Percentage of Normal
Business hours.
Note–We must measure overall service
availability. The maximum threshold is the
maximum outage per incident and/or total sum
of outage per month.
Insert percentage of service name transactions will
exhibit insert value seconds or less response time,
defined as the interval from the time the user
sends a transaction to the time a visual
confirmation of transaction completion is
received. Missing the metric for business
transactions measured over any business week
constitutes a violation.
Percentage of transaction response times more
than x seconds.
Note–We must measure transaction times
against a threshold of x seconds and measure
the number of slower transactions as a
percentage of the total.
The IDC Customer Care team will respond to
service incidents that affect multiple users
within insert time period, resolve the problem
within insert time period, and update status every
insert time period. Missing any of these metrics
on an incident constitutes a violation.
Service Incident (affecting multiple users)
Response times, resolution times and status
updates.
Note–We must be able to create incident reports
that track actions with timestamps. These are
measured against the time thresholds.
The IDC Customer Care team will respond to
service incidents that affect individual users
within insert time period, resolve the problem
within insert time period, and update status every
insert time period. Missing any of these metrics
on an incident constitutes a violation.
Service Incident (affecting single users)
Response times, resolution times and status
updates.
Note–We must be able to create incident reports
that track actions with timestamps. These are
measured against the time thresholds.
The IDC Customer Care team will respond to
non-critical inquiries within insert time period,
deliver an answer within insert time period, and
update status every insert time period. Missing
any of these metrics on an incident constitutes a
violation.
Inquiry response times, answer times and status
updates.
Note–We must be able to create incident reports
that track actions with timestamps. These are
measured against the time thresholds.
The external availability measurements are done
by insert test company name and reported on a
monthly basis to customer name. The internal
processes are measured and reported by the ISP
to the customer name on a monthly basis.
This is an example of an external management
service that is managed by its own SLA between
the IDC provider and the external ISP that
supports this commitment to the service
consumer.
Why a Service Level Agreement is Important 7
FIGURE 1 Transaction Response Times for Promised Service Levels
Why a Service Level Agreement is
Important
A good SLA is important because it sets boundaries and expectations for the
following aspects of data center service provisioning.
n Customer commitments. Clearly defined promises reduce the chances of
disappointing a customer. These promises also help to stay focused on customer
requirements and assure that the internal processes follow the right direction.
n Key performance indicators for the customer service. By having these indicators
established, it is easy to understand how they can be integrated in a quality
improvement process (like Six Sigma). By doing so, improved customer
satisfaction stays a clear objective.
n Key performance indicators for the internal organizations. An SLA drives internal
processes by setting a clear, measurable standard of performance. Consequently,
internal objectives become clearer and easier to measure.
n The price of non-conformance. If the SLA has penalties (something that many IDC
providers prefer to avoid but should not) non-performance can be costly.
However, by having penalties defined, the customer understands that the IDC
provider truly believes in its ability to achieve the set performance levels. It
makes the relationship clear and positive.
Example metrics:
- Client tests
connected through
major ISPs such
as AOL
- Ping tests
Example metrics:
- Transaction
response time
Example metrics:
- CPU utilization:
% of total process
- I/O response in ms
- Memory utilization
Example metrics:
- Bandwidth
utilization:
% of total
protocols
- Throughput in ms
- Ping tests
Internet
3 seconds
Application
3 seconds
SLA time
10 seconds
Systems
2 seconds
Network
2 seconds
8 Building a Service Level Agreement in the Data Center • April 2002
Benefits of Measuring Against an SLA
This chapter describes why measuring against SLAs is so important to a successful
data center service and a healthy infrastructure.
Key to success for a data center service is the ability to perform according to
predefined standards. Performance is summarized as the ability to meet (or
preferably exceed) the customer’s expectations. The first step is to set realistic
expectations for both sides of the contract. An SLA is a great vehicle to communicate
the expectations and create a level of trust by adding conditions and penalties when
the promises are not met.
The SLA defines a clear relationship between the customer and the provider by
setting boundaries, conditions, penalties and expectations.
Because an SLA links the customer requirements to infrastructure requirements, it
creates the ability to link service levels to service cost and, as a result, profitable
pricing can be set. Moreover, by spending wisely on well defined requirements
rather than rules of thumb or gut feeling, more efficient cost management can be
achieved.
The capability to segment service offerings with different pricing for different
service levels benefits both the vendor and the customer. The vendor widens its
target market by being able to customize its services and the customer only pays for
what it needs.
Having the ability to measure against key performance indicators facilitates the
continuous quality improvement process. Being able to raise the performance bar at
a steady pace helps the data center service provider to remain competitive. By tying
the problem resolution process to an SLA, a service performance problem becomes
an opportunity to structurally improve overall service quality and customer
satisfaction, as opposed to just resolving the symptoms of the real issue.
An SLA sets the standards to which the IDC service provider committed. As a result,
a set of common and/or global parameters is derived to which all organizational
groups must be managed and measured. Requirements for success of the business
are now directly translated to measurable requirements for the technical teams.
The SLA drives the definition of Key Performance Indicators (KPIs) at the service,
application, system and network level. Defining these KPIs facilitates the proper
tools selection, process definitions and skills (people, process and technology) for an
organization.
Knowing what to measure eliminates redundant data collection, which reduces the
total overhead of the SLM system on the service infrastructure. A good SLM system
collects data only once.
Recommendations 9
Recommendations
The following is a set of suggestions based on our experience in writing and
managing against SLAs.
1. Keep the agreements simple, measurable and realistic.
This technique creates clarity and keeps the process simpler. Just think of all the
hours attorneys will charge to unfold a complex agreement. Being measurable
also improves the ability to perform according to the agreement. Realistic goals
can be achieved and the penalties can be limited.
2. Bring business managers and technology managers together during the definition
of the customer SLAs.
By doing so, promises made in the SLA will be able to be met by the underlying
technology. The challenge is that the initial SLA should be the basis for internal
technology choices, and the underlying technology should help define the
limitations of the initial promises in the SLA. This is a “catch 22”. The best way to
break the catch is to ensure that technology and business managers come together.
3. Map the commitments to KPIs and have these indicators drive the performance
metrics of the business units.
Summary
In this article, we explained what an SLA should look like and how it supports the
SLM process.
We also gave examples to show the key elements in an SLA:
n What the provider is promising.
n How the provider will deliver on those promises.
n Who will measure delivery, and how.
n What happens if the provider fails to deliver as promised.
n How the SLA will change over time
We have shown two templates to illustrate how these principles can be translated in
real examples. Remember that every business is unique and that one should be
flexible in applying these principles.
10 Building a Service Level Agreement in the Data Center • April 2002
We mapped the commitments in an SLA to KPIs to help facilitate the performance
metrics definition. These KPIs drive the internal goals and even influence the tool
selection of the SLM system as explained in the Service Level Management in the Data
Center article.
We have described the importance of SLAs to avoid the most common pitfall as
quoted by nextslm.org: “The IT industry has a history of over-promising and underdelivering.
This history repeats itself in the ASP model, with promises of absolute
(99.99999%) reliability, global availability and rock bottom costs.“
The benefits of a good SLA are many, but the most important ones are:
n Sets clear customer relationships
n Sets goals for internal organizations
n Sets a framework for continuous quality improvement
n Drives the SLM system architecture
We ended with some suggestions to assure the creation of good SLAs. The most
important one is to keep the SLA simple, measurable and realistic.




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