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Case Studies
Active/Active Payment Processing at
Swedbank (3,1) Swedbank uses
active/active Base24 to support credit cards and POS terminals.
Asymmetric
Active/Active at Banco de Credito
(2,11) Using an symmetric configuration save programming
changes.
Bank-Verlag - the
Active/Active Pioneer (1,3)
Bank-Verlag went active/active two decades ago with IBM/Tandem.
BANKSERV Goes Active/Active
(2,4) A banking switching service in South
Africa moves Base24 into active/active.
Community College
Learns From SAN Disaster (2,2) A
disastrous SAN failure leads to dual redundancy.
CPA
at Aqueduct, Belmont, and Saratoga
(2,1) Race
track wagering can never fail, or else riots start.
Do
You Know Where Your Train Is?
(1,1) A transit authority goes active/active for train
tracking.
How Does Google Do It? (3,2)
Google processes tens of gigabytes of data in minutes on their
massive clusters.
HP's Active/Active Home Location Register
(1,2)
The brains of a cellular network can never go down.
HP's
OpenCall INS Goes Active/Active (2,6)
Replication lets OpenCall INS run active/active with collision
detection and resolution.
Major Bank
Uses Active/Active to Avoid Hurricanes
(2,10) Fast failover is used to switch users out of
hurricane path.
Payment
Authorization - A Journey from DR to Active/Active
(2,12) A start with DR leads this company to active/active
and application integration.
QEI
Provides Active/Active SCADA with OpenVMS
(2,9) Electrical substation monitoring that never
goes down.
Tackling
Switchover Times
(1,1) If active/active is too big a step to take now, work
on reducing your switchover times.
Telecom
Italia's Active/Active Mobile Service
(2,3) Italy's biggest cell phone network is supported by
active/active.
Never Again
Active/Active Save #1 - Coffee Pot Takes Down Node
(1,2) When the coffee pot was plugged in -
Surprise!
BlackBerry Gets Juiced (2,5) Poor
testing leads to no service for North American subscribers.
BlackBerry Takes
Another Dive (3,3) Deja Vu. Poor
testing once again leads to no North American service.
Console Command Takes Down Active/Active System
(1,3) Stop applications on one node, stop
other node. Oops!
Don't
Wait for the Other Shoe to Drop (2,2)
When a spare component fails, fix it fast. Don't tempt Murphy.
Hostway's Web Hosting
Service Goes Down for Days (2,9)
Small online stores offline for up to a week.
How Many 9s in Amazon? (3,7) Even
giants fall. Amazon's S3 and EC2 services and online retail
store go offline for hours.
IRS Goof Costs U.S.
Taxpayers $300m + (2,1) Turning
off the old system before testing the new one is dumb.
On-Demand Software
Utility Hits Availability Bump (2,10) A
utility is expected to be always up, but this one didn't make
it.
PayPal Services Downgrade with Upgrade
(3,6) Attempting an upgrade with no fallback plan takes
PayPal services down for weeks.
Rackspace - Another
Hosting Service Bites the Dust (2,12)
A truck driver wipes out web sites for a day or more.
So You Think Your System is Robust?
(2,8) So did these major enterprises, all of which went
down in the first six months of 2007.
So You Think Your System is Reliable
(3,1) Horror stories from the second half of 2007 focus on
power and branch failures.
Software
Bug Causes Train Wreck (1,1)
A software bug, controller diversion, and engineer inattention
combine to cause a train collision.
The Alaska Permanent Fund and the $38 Billion Keystroke
(2,4) What do you do when your active and backup disks are wiped
out and your tapes won't read?
The
Case of the Flying Cable
(1,1) A technician loses control of an under-floor cable
and lets it hit a power strip.
The
Great 2003 Northeast Blackout and the $6 Billion Software Bug
(2,3) A hot day, an untrimmed tree, and a monitoring
system bug cost power customers $6 billion.
Triple
Redundancy Failure on the Space Station
(0211) A single point of failure takes down a triplexed
critical computer.
VoIP
PBX Succumbs to Overconfiguration (2,6)
Why extra processing power made this PBX less reliable.
What? No Internet?
(3,2) A multiple cable break isolates North Africa, the
Middle East, and India.
Best Practices
Availability
Best Practices (2,1) Tips from
those who have achieved near-continuous availability.
Can 10,000 Chickens Replace Your Tractor?
(1,3) Save money by replacing your mainframe with
clusters - Not!
Document Your
System (1,2) Documentation is a
necessary evil. Let's focus on the "necessary" and not the
"evil."
HP
Blows Up Data Center (2,8) An explosive
demonstration of fast recovery.
Humanizing Three 9s (2,9) What if
we lived in a world of three 9s?
Interview
with Ron LaPedis on NonStop with XP Storage
(2,5) How to improve NonStop reliability by using a SAN.
Katrina -
The Harsh Teacher (2,6) The most
powerful Gulf storm in 200 years showed us how unprepared we
were for such a disaster.
On Blogs and Discussion Groups (2,10)
Online forums can be a big boost to your professional growth.
Reliable Multicasting
(3,1) How to get messages over LAN and WAN multicast
networks without message loss.
Recovery-Oriented Computing (2,2)
If recovery time can be made small enough, users will perceive a
faultless system.
Microrebooting for Fast Recovery
(2,3) An application of Recovery-Oriented Computing.
Rules
of Availability - Part 1 (3,3)
The first set of common rules of availability from our books,
Breaking the Availability Barrier.
Rules
of Availability - Part 2 (3,5)
More common rules of
availability from our books,
Breaking the Availability Barrier.
Rules
of Availability - Part 3 (3,7)
Concluding the common rules of availability from our books,
Breaking the Availability Barrier.
Transaction-Oriented Computing (2,4)
Old art to some, new to others, transaction processing is the
foundation for high availability.
With
100% Uptime, Do I Need a Business Continuity Plan?
(1,1) You'd better believe it.
Availability Topics
Active/Active Versus
Clusters (2,5) For high
availability, clusters are mature; but active/active systems
provide greater reliability.
Adding
Availability to Performance Benchmarks
(2,9) A system that is down has zero performance.
All
About Continuous Processing Architectures
(1,1) CPA can get you
arbitrarily close to 100% uptime.
Asynchronous
Replication Engines (1,2) These engines
power most of today's active/active systems.
Availability versus Performance (2,8)
Is it time to trade higher availability for reduced performance?
Collision Detection and Resolution
(2,4) What do you do if you can't avoid collisions when
using bidirectional replication?
Fault
Tolerance for Virtual Environments - Part 1
(3,3) How virtualization can significantly reduce
data center capital and operating costs.
Fault
Tolerance for Virtual Environments - Part 2
(3,4) Operating system and bare metal hypervisors.
Fault
Tolerance for Virtual Environments - Part 3
(3,6) Hardening virtual environments
with failover and fault-tolerance.
Hardware
Replication (2,1) Replicating at
the hardware level does not maintain database consistency.
Jim Gray - In
Memoriam (3,7) The database
pioneer that set the stage for active/active systems is lost at
sea.
Let's
Get an Availability Benchmark (2,6)
Great performance is meaningless if the system in unavailable.
Migrating
Your Application to Active/Active
(2,3) What must you do to prepare your application for an
active/active environment?
Synchronous Replication (1,3)
Avoid data collisions and data loss following a node failure.
Time
Synchronization for Distributed Systems - Part 1
(2,11) How does NTP calculate the time offset from a time
server?
Time
Synchronization for Distributed Systems - Part 2
(2,12) How NTP minimizes time offset
errors?
Time Synchronization for Distributed
Systems - Part 3 (3,2) Logical clocks
offer an option for synchronizing systems.
Transaction
Replication (2,2) A simple
approach to active/active systems
has scalability issues.
The
History of Fault Tolerance (1,2) The
fault-tolerant marketplace was hot in 1984.
What
is Active/Active?
(1,1) Active/active architectures
can give subsecond recovery following a failure.
Recommended Reading
Aberdeen's 2008
Business Continuity Survey (3,4)
A look at 150 small to large companies and their BC/DR plans and
processes.
Blueprints for High
Availability: Designing Resilient Distributed Systems
(2,5) All you ever wanted to know about
clusters.
Breaking the Availability Barrier
(3,5) Everything you ever wanted to know about
active/active systems - theory, implementation, and practice.
Business
Continuity Planning: IT Examination Handbook
(1,1)
What better way to learn about BCP than from the auditor's
handbook.
Continuous Availability Systems Design Guide
(2,1) What to do if you want to move to CPA.
Distributed Systems: Principles and
Paradigms (3,1) A thorough treatment
of requirements for distributed system transparency.
Fire in
the Computer Room , What Now? (2,6)
Are you prepared for a total loss of your data center because of
a fire or other disaster?
Migrating Legacy
Systems: Gateways, Interfaces, & the Incremental Approach
(2,3) Legacy
systems must be decomposed to migrate to active/active.
Multiple Processor Systems for Real-Time Applications
(2,10) A classic treatise on distributed systems
that is still pertinent two decades later.
The
Business and Economics of Linux and Open Source
(1,3) Open source demystified for the
reluctant manager.
The Unified Modeling Language User Guide
(1,2) UML is now the accepted standard for fast
and easy documentation of systems and procedures.
Towards
Zero Downtime: High Availability Blueprints
(2,8) A close look at installing Microsoft clusters and
cluster-aware applications.
Transaction Processing: Concepts and Techniques
(2,4) The classic book on transaction processing
systems, by Jim Gray and Andreas Reuter.
Unix Backup and
Recovery (2,2) Backing up is a
pain, but it is the restore that counts.
Product
Reviews
Fault-Tolerant
Windows and Linux from Stratus (2,9)
ftServers provide transparent fault-tolerant operation.
Flexible
Availability Options with GoldenGate's TDM
(2,2) Implement a variety of data-sharing
topologies with TDM's data replication facilities.
GRIDSCALE - A Virtualized Distributed Database
(3,7) Like presentation and application servers, pooled
database servers for the three-tier archictcture.
How
Much Will Active/Active Cost Me?
(1,1) The cost of downtime can swing your
decision.
HP's
ServiceGuard Clustering Facility (2,5)
Managing HP-UX and Linux clusters.
MySQL Clusters Go Active/Active (1,3)
Clusters of storage nodes are kept in sync by synchronous
replication.
OpenVMS Active/Active
Split-Site Clusters (3,6) OpenVMS
Clusters provide active/active operation with synchronous
replication.
Parallel Sysplex
- Fault Tolerance from IBM (3,4) IBM's
Parallel Sysplex offers offers localized active/active
availability.
Penguin
Computing Offers Beowulf
Clustering on Linux (2,1) Beowulf
clustering, developed by NASA, is available on Linux along with
Penguin's HPC servers.
Shadowbase - The
Active/Active Solution
(2,3) Shadowbase provides fast data replication as well as
online copy and database resynchronization.
solidDB - a Five 9s Memory-Resident
Database (3,5) Server
memory is getting so large, why not keep your database in high
speed memory?
Time
Synchronization for NonStop Servers
(0211) NTP products from Bowden Systems and HP for
NonStop servers.
Virtual
Tape - Getting Rid of a Troublesome Medium
(1,2) The backup paradigm is changing.
Goodbye, tape.
Virtual
Tape for NonStop Servers with ETI-NET's EZX-BackBox
(2,6) Virtual tape made super-fast with
deduplication.
Virtual Transactions with NonStop AutoTMF
(2,4) Converting nontransactional applications
to transactional applications.
The Geek
Corner
Calculating
Availability - Redundant Systems (1,1)
Some useful
rules come out of the derivation of the availability equation.
Calculating Availability - Repair Strategies
(1,2) Your repair policy can have a significant
impact on your system availability.
Calculating Availability - The Three Rs (1,3)
Node repair, node recovery, and system restore are all required.
Calculating Availability - Hardware/Software
Faults (2,1) Most faults
don't need a repair.
Calculating Availability - Failover (2,2)
When a system is failing over, it is often effectively down,
thus reducing availability.
Calculating Availability - Failover Faults
(2,3) Failovers can fail also.
Calculating Availability - Environmental Faults
(2,4) How to handle hurricanes, power failures,
and riots when calculating availability.
Calculating Availability - Nodes, Subsystems, and Systems
(2,6) When is a node a system, and when is
it a subsystem?
Calculating Availability - Failure State Diagrams
(2,9) Formalizing our intuitive
derivations.
Calculating Availability - Heterogeneous Systems - Part 1
(3,3) Probability 101 in preparation for analyzing
systems with heterogeneous nodes.
Calculating Availability - Heterogeneous Systems - Part 2
(3,5) The availability of redundant systems with
different nodal availabilities.
Calculating Availability - Heterogeneous Systems - Part
3 (3,6) Analyzing complex
configurations of system components.
Failure State Diagrams - Repair Strategies
(2,10) The real story behind sequential repair
and parallel repair.
Failure State Diagrams - Recovery Following Repair
(2,12) The formal analysis of the impact of having to
recover a node after its repair.
Failure State Diagrams - Hardware/Software
Faults Revisited (3,2) Our intuitive
results were a little simplistic.
Cluster Availability
(2,5) How does the availability of a cluster compare to
that of an active/active system?
Estimating Data Collision Rates (2,8)
Can you go active/active with a tolerable level of data
collisions?
Is Parallel
Repair Really Better Than Sequential Repair?
(3,4) A Digest reader points out that that depends upon the
repair time distribution.
What's
That Nerd Logo?
(1,1) Our logo,
ff2,
really has a meaning. Find out why it describes active/active
architectures.
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