TECHTARGET.COM: The Information Architect
Builders of the 21st Century IT Infrastructure
SPONSORED BY: EMC
New IDC Whitepaper on Lowering TCO: EMC Customers Report up to 9X
Cost Efficiencies
A recent IDC study based on interviews with EMC customers reveals
dramatic cost savings--all directly attributable to an EMC enterprise
information infrastructure:
* 9:1 improvements in personnel efficiencies
* 85-90% storage capacity utilization (40-50% gain over prior
solutions)
* Storage administrators can manage up to 12TB of data versus 1.3TB
* Redeployed staff can generate revenue opportunity of up to $10M
each
Download the IDC whitepaper and learn more about how EMC helps
customers lower the total cost of ownership of storage
infrastructure.
http://ad.doubleclick.net/clk;3039963;5058249;r?
http://www.emc.com/techtarget/v9/index.html
Web load balancing
Before you investigate this method, take some time to understand the
current performance of your Web site and where the current or
potential bottlenecks are located.
by Johanna Ambrosio
Load balancing your Web site is something to consider whether you're
selling billions of dollars' worth of goods online or are a
mom-and-pop shop with a much smaller site. Load balancing basically
means that you divide the amount of work that a computer has to do
between two or more computers.
The key benefit is that load-balancing hardware and software allow
requests for information and other "hits" to the site to be
automatically redirected to a free server, thus evening out the
traffic load so that visitors don't need to wait overly long for
their answers.
So says Nigel Hughes, the service leader for e-commerce at Compass
Management Consulting Ltd., a global firm specializing in business
and IT performance improvement for Fortune 1000 organizations.
Hughes, who works out of the London office of Compass, re
To continue reading for free, register below or login
To read more you must become a member of SearchSOA.com
cently
addressed the issues surrounding Web load balancing.
Why should companies consider load balancing?
Load balancing will allow them to increase reliability, performance
and make maximum use of their current investments.
An analogy is with checkouts in a grocery store. If you are in a
checkout line and can see that another checkout is free, then you
would probably move across. The same applies to processing requests
to a Web site. You don't want expensive server resources sitting
underutilized while others are struggling to keep up with demand.
Load balancing can also go further in that it is able to use multiple
checkouts per person. So where the family of eight has a month's
worth of groceries in one cart, load balancing can break up the
contents of the cart and distribute it across several checkouts, thus
speeding up the average service time.
Does load balancing work?
The simple answer is yes, but care must be taken in choosing an
appropriate solution in terms of cost and performance. Best practice
states that you ensure that there is redundancy built into your
load-balancing solution. The last thing you want to do is introduce a
high-cost, complex solution that acts as a single point of failure.
The key characteristics of a robust solution are:
-The load should be dynamically speeded among server resources,
giving clients best possible performance.
-The service should remain available during planned and unplanned
downtime.
-You should be able to increase your capacity without disruption
to service.
Before investigating load balancing, take some time to understand the
current performance of your Web site and where the current or
potential bottlenecks are located. Typically, bottlenecks include
server utilization and network bandwidth.
Next, look to the future and make some estimates on growth.
Finally, have a look at your budget.
What are the various load balancing techniques?
There are a number of techniques, and they generally fall into the
following three categories:
-Simple routing, or DNS round robin
Simple routing is when a list of servers is maintained and requests
are routed to a specific server based on the address requested. DNS
round robin adds to this by maintaining a similar list but when a
request comes in it is assigned to the next server on the list until
the end of the list is reached. The next request is then assigned to
the first server again and so on. The advantage of these methods is
simplicity, and as long as you either have relatively light or
consistent traffic requests coming in it works very well. There is no
prioritization of traffic. More complex or more important requests
receive equal priority with all other requests.
-More complex routing algorithms
Requests can be distributed based on performance of the servers
(fastest servers get more load), the type of server (i.e. this
request needs something special that's only available on particular
server) or by customer priority. This works well for heavy loads, but
there can come a point when a threshold is reached where the load
balancing solution becomes the bottleneck.
-Intelligent routing
This balances load based on the content of the request. It can also
handle session failures so that orders, for example, can be
redirected transparently in the event of failure.
What are the vendors offering?
Vendors offer two types of solutions:
-Dedicated load balancing devices: expensive, suitable for the
enterprise, out of the box with little configuration necessary, very
fast and very reliable. Upgrades are limited because they require new
or upgraded hardware.
-Server based: software is installed directly on either a dedicated
server or application servers. Lower upfront costs, flexibility and
fine-tuning, but with steep learning curve and additional
administration cost. Upgrades are generally cheaper and simpler, due
to how only the software needs to be upgraded.
What options exist outside of load balancing for managing heavy Web
traffic?
You can outsource; increase server capacity; improve the design of
your site; use RAID hardware; provide bandwidth on demand to handle
expected peaks, and partition the load by the servers.
How might one go about making a decision?
You should make sure that the solution you choose can handle
monitoring, reporting and accounting. The solution should be able to
monitor traffic analysis such as response times, bandwidth
utilization and errors. It should also have accounting features to
let you look at traffic by groups of users and content accessed. Also
consider the ongoing cost of administration as well as lease/purchase
cost. Find out what others have done, and make sure it's scalable so
it fits in with your future growth plans. Leased solutions are often
good from this perspective.
Also factor in the cost of not doing it. The magic 8-second figure is
often cited: If a page load takes longer than 8 seconds customers
will go somewhere else. Load balancing can considerably improve
response time, especially during peak activity.
Finally, load balancing is a technical and complex subject with a
multitude of solutions. But also remain focused on the key aspects:
understand what you are trying to do, what you will need to do in the
future, what skills you have access to and what your budget is. Don't
get carried away with the wondrous technical possibilities that
exist. As Einstein said, "Make it as simple as possible, but no
simpler."
Ambrosio is a freelance writer in Marlborough, Mass.; write her at
jambrosio@mediaone.net
MORE INFORMATION ON THIS TOPIC:
You'll find links to how to manage e-commerce Web site issues in
this section of searchEBusiness
SearchWebManagement offers you an abundance of links on Web
performance and management.
