ICAITS021C Connect internal hardware components
ICAITS030B Install software to networked computers
ICAITS116B Undertake capacity planning
Question 1: What is meant by capacity planning in information technology?
Answer Suggestion:
Capacity Planning is the activity relating to the management of the information communication infrastructure to ensure that the output of the facility is maximized and the input is minimized.
The activity involves the use of tools to measure inputs and outputs that may be competing. Constraints come in the form of labour, material availability, equipment utilization and limited space. Planning, the use of mathematical models and flexibility in resource utilization is needed
Capacity planning in information communication technology systems is needed when:
Starting a new system, or a service organization
Extending the operations of an existing business system.
Considering additions/modifications to the system
Introducing new techniques, equipment and materials
Question 2: What are some of the factors that capacity planning needs to consider?
Answer Suggestion:
Bottlenecks that will determine the capacity for any particular stage of the process.
Peak demand rate
Communication Bandwidth
Load balance within the system
Existing Hardware and scalability
Cost
Technology changes in hardware and software
Question 3: Briefly describe the following terms
a. Design Capacity
Answer Suggestion:
Target output level
Note: It could be reached or exceeded in practice.
It is the agreed % between vendor contractor and customer of the system
b. Effective Capacity
Answer Suggestion:
It is the actual capacity to reflect current conditions.
Note: could be less than or more than design capacity.
Required because of; limited resources, increased equipment breakdowns when run at higher capacity for long periods and the impact of the environment.
c. Utilization
Answer Suggestion:
Measures use of resources i.e actual running time.
Measure as % of effective capacity.
Note: measurement is often different between organizations and systems.
d. Yield
Answer Suggestion:
Measures output of product in % against equivalent, potential or maximum products or systems’ input.
Question 4: What are the stages in capacity planning?
Answer Suggestion
1. Analyse existing system capacity
2. Determine future capacity requirements
3. Plan for capacity enhancement
4. Install capacity enhancements
Question 5: Describe some of the commerce site metrics in capacity planning for a business that is moving into e-commerce.
Answer Suggestion
a. Hits: Results of multiple hits from the browser to the Web server
A hit is any request from the browser to the Web server this includes requests for dynamic content, images, or streamed video
b. Average hits per page: The average number of Web server hits per page.
The suggested configurations used stores with 1 hit per page. The test tool did not load any images, nor did it use frames. The test tool only made one HTTP request per page.
c. Commerce/non-commerce page ratio
Most pages are generated by issuing a database query and rendering the results by using JSP (Java Server Page) templates.
Typical stores also contain some static content, such as HTML page requests. The suggested configurations did not contain any requests for purely static pages. Static pages are served at roughly the same rate as static images.
Requests for static pages can be ignored in capacity planning, if the ratio of dynamic requests to static requests is fairly high. A site which serves two dynamic pages for every static page can be sized without regard for the static pages.
This is because dynamic pages require substantially more resources to serve.
d. Database size
The database size affects performance of the system. Sites that include many shoppers, merchants, or catalogue items usually cannot serve requests as quickly as those that do not.
Various factors will affect the throughput of the system, including database tuning, hardware capacity, and physical topology.
e. Megabytes of data that are served per unit of time
It is important to plan your site to have sufficient resources for serving expected network throughput. This includes sizing all firewall, routing, and other network components to be able to handle the peak workload expected of your site. The suggested configurations can be measured using a full duplex 100 Mbps Ethernet between the load generator and Web server.
A 100 Mbps switch can be used between the Web server and database server.
It must be noted that added equipment results in the Internet communication being significantly slower.
If the site is running web casts or real time audio, this will demand bandwidth. This has to be taken into account in the overall capacity planning solution.
f. Performance Test Scripts
The commands executed affect system workload.
Te set up and the commands run as part of performance tests can be like the following.
Components:
A basic store that contains a set of use cases commonly used in shopping model:
– New shopper registration
– Registered shopper logon
– Browse categories, products, and items
– Add item to shopping cart
– View shopping cart with tax and shipping details
– Modify quantity of items in the shopping cart
– Delete items from the shopping cart
– Checkout by entering billing and shipping information
A script to generate the following:
– Up to 5 000 categories
– Up to 50 000 items
– Up to 50 000 registered customers
– Up to 50 000 orders
A script to simulate various shopper scenarios
– Browse
– Add
– Prepare
– Buy
A script to define the regular shopping mix
The regular shopping mix depends on two variables:
1. Customer type
New registered customer
Existing registeGuest shopper
2. Shopping flow
Browse
Visit the home page
Logon using registered customer id (existing registered customer only) or register as a new customer (new registered customer only
Select “Multiple Category Display” then “Multiple Product Display”
Browse and Add
Browse, and then randomly add one, two, or three items to the shopping cart.
Browse and Prepare
Browse and add, then enter address book information (guest shopper only) or specify which address to use (new registered customer or existing registered customer).
Browse and Buy
Browse and prepare, then display order information. Enter a credit card number with expiry date, finally submit the order.
Question 6: Describe some of the differences in a corporate site as against a high-end e-commerce site that directs the activities for capacity planning red customer
Yield is concerned with avoidable and unavoidable losses due to downtime as a result of system or equipment problems. qqq
Question 7: Describe the steps in capacity planning for your organization that has moved onto e-commerce utilization of computer systems
Answer Suggestion
Steps
1: Complete a worksheet with calculated system capacity metrics.
2: Select the number of server tiers
3: Determine requirements for availability
4: Select hardware
5: Configure the appropriate number of disk drives
6: Configure memory for each system
7: Configure the network requirements
8: Is a separate Payment Manager server required?
9: Is a separate server required for search?
10: Will a Staging server be used?
Capacity planning information
Capacity planning is the key to a well-oiled, smooth-running data center, helping IT organizations to:
*Accurately and efficiently provision new applications
*Reduce, delay and sometimes completely avoid costs
*Justify upgrades with objective analyses
*Optimally configure systems to accommodate forecasted changes in business
*Migrate systems to take advantage of new technology
*Consolidate servers to simplify management and gain economies of scale
*Mitigate service delivery risk by playing out potential scenarios in advance, and then preparing for them
Capacity Planning Techniques
A variety of capacity planning techniques are available, each useful in its own right. TeamQuest provides tools for each of these techniques:
Trending
Trending uses simple extrapolation of resource utilization over time. The advantage of this technique is that it does not require sophisticated tools. A spreadsheet will do, but it can be difficult to take into account non-linear behavior buried deep within a multi-tiered system.
Linear TrendAnalysis
Linear trend analysis looks at historical data and projects a linear trend line into the future, applying upper and lower confidence intervals as well as a threshold at which resources will become inadequate. This capacity planning method is a quick sanity check and identifies over-utilized resources, but it does not allow for experimentation with different configurations.
Short TermAnalysis
Short term analysis identifies potential problems early by generating exception events (alarms) based on historical averages (rather than a fixed threshold) tied to a particular point in a periodic time interval. For example, if a particular resource averages 60% busy on Tuesdays and 50% busy on Thursdays, an exception event will only be generated when utilization crosses those thresholds on the respective days.
SimulationModeling
Simulation, a much more sophisticated capacity planning technique than trending, actually simulates the queuing events that occur during execution. The downside of simulation modeling is that it can be very time-consuming to build and run the models.
AnalyticModeling
Analytic modeling uses mathematics to calculate how a queuing network will perform. To use analytic modeling, a baseline set of measurements is taken on a system and a model is then built based on a description of the system. Results from the model are compared with the baseline, and when they match, the model is considered calibrated. From there, hypothetical changes can be made to system configuration or business workloads, and the model will predict how the changes will affect performance. Done properly, analytic modeling is a fast and accurate capacity planning technique.
Analytic Modeling and Load Testing
Especially when rolling out new applications, it can be useful to use a load-testing tool in conjunction with an analytic modeling tool.
A load-testing tool can be used to simulate transactions coming from end users, or applications can be benchmarked on test systems to be certain they can support required service levels. However, time and cost considerations often make it prohibitive to conduct such tests on the actual hardware using production-level workloads. Full-sized machines and software are too costly to dedicate for testing purposes, and finding the optimal configuration through empirical testing can take a long time.
Instead, smaller but representative loads can be applied to a scaled-down set of test servers while performance analysis software takes a baseline reading of performance. Analytic modeling can then be used to rapidly predict how various configurations will perform under a production-level workload, all without the need to purchase the actual configurations under consideration. Analytic modeling is a cost-effective, fast and accurate alternative to brute-force testing.
No comments:
Post a Comment