Minimal Impact Database Migration

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Case Study Teach for America COMPLETES DATABASE MIGRATION

WITH MINIMAL IMPACT ON END USERS

© Copyright 2018. All Rights Reserved. HVR Software.

MINIMAL IMPACT DATABASE MIGRATION

CASE STUDY SNAPSHOT

Customer Teach for America

Challenge Migrate production database from Oracle to SQL Server with minimal downtime

Solution HVR enabled the team to complete migration tasks in stages, rather than requiring a Big Bang migration.

Results HVR minimized disruption to website users, requiring only ½ day of downtime. Without HVR, the organization estimates the cutover would have taken several days.

Databases • Oracle • SQL Server

Use Case • Database migration

“Because HVR was one of the few solutions that could replicate between

disparate databases in a cost-effective manner. Other solutions either didn’t work,

cost a lot, or didn’t do what we needed.”

Larry Blake, Managing Director, Enterprise Data Services at Teach for America

SolutionThe organization chose HVR to perform the data migration, says Larry Blake, Managing Director, Enterprise Data Services at Teach for America, “Because HVR was one of the few solutions that could replicate between disparate databases in a cost-effective manner. Other solutions either didn’t work, cost a lot, or didn’t do what we needed.”

To keep the website operational during as much of the migration process as possible, the organization decided to complete the migration in stages. First, the team moved reporting from Oracle to SQL Server. It built a new SQL Server data warehouse for reporting while allowing the website to continue to run off the old Oracle-based transactional system. For several months, the team used HVR to replicate data between the Oracle and SQL Server systems.

Once the team was comfortable using SQL Server for reporting, it used HVR to migrate the Oracle-based transactional system to an SQL Server-based transactional system. Ultimately, the new transactional system was used to feed the separate SQL Server data warehouse.

BackgroundTeach for America is a not-for-profit organization dedicated to ensuring that all children have access to an excellent education. It puts high-achieving young people into under-resourced, struggling schools with the aim of changing students’ lives for the better and producing civically minded leaders. Today, the organization has more than 55,000 corps members and alumni and has reached millions of students across 53 regions of the United States.

Teach for America relies heavily on its website to recruit prospective teachers. Prospective teachers use the site as a portal to obtain information about the program and apply to it. So, when the time came to migrate the Oracle database that supported the website to Microsoft SQL Server, the organization needed to minimize downtime. The IT team relied on HVR to simplify and speed this database migration process.

ChallengeTeach for America was using an Oracle database to manage all the data about its applicants, current teachers and former teachers. The organization made this data accessible to potential, existing, and former teachers through a portal on its website. It also used the same Oracle database internally to store general business information and enable reporting.

As a not-for profit organization, Teach for America must constantly be on the look out for ways to be a better custodian of its funds. It decided to migrate its Oracle database to Microsoft SQL Server to improve its financial stewardship as well as address evolving business needs. As it performed the six-month migration process, a major challenge the team faced was finding ways to minimize disruption for website users.

“We appreciated the fact that HVR allowed us to override the suggested format and respected our override. That made creating new tables and doing the replication very easy to do.”

Larry Blake, Managing Director, Enterprise Data Services at Teach for America

© Copyright 2018. All Rights Reserved. HVR Software.

ResultsMinimal DowntimeUsing HVR, the Teach for America reporting and Java development teams were able to finish their own parts of the migration on different schedules, rather than having to complete everything Big Bang. Most steps were completed without impacting the website, allowing Teach for America to limit downtime of the website to just half a day.

As the team migrated the data from Oracle to SQL Server, it needed to reconcile differences in data formats between the two products. HVR offers capabilities that automatically create mappings between source and target tables. It also provided the flexibility that enabled the Teach for America team to override the defaults, where necessary, and define some of the formats it wanted to use.

For example, Oracle time stamp columns have no exact equivalent in SQL Server. The team wanted to make the formats adhere as closely as possible to SQL Server best practices. So, while the IT team used HVR to automatically create new data tables in the target based on the format of the source, in cases where the suggested format was not a SQL Server best practice, they created the data tables manually.

Another issue during the migration was that two teams were working on the project simultaneously: The database team and the Java team in charge of the website. Sometimes the database team would choose a default and the Java team would request a different option. Other times the Java team would create a new feature at the same time the database team was migrating data. The new feature might result in the addition of new data columns. HVR simplified the process of adjusting to those changes and discrepancies by allowing the team to reload individual tables when necessary, rather than requiring them to reload the entire database.

The HVR consulting team provided excellent service to assist with these intricacies during the migration.

“Our website is pretty busy. Having it unavailable for any length of time is highly undesirable. The fact that we were able to get our downtime window to half a day was huge. Without HVR, we would have had to perform the entire migration at once—and the end-to-end time for getting back to business would have been days.”

Larry Blake, Managing Director, Enterprise Data Services at Teach for America

“The trainers were very knowledgeable about the product and generous with their time. They got us up and running very quickly. We were very pleased with the service and had a very good experience.”

Larry Blake, Managing Director, Enterprise Data Services at Teach for America

HVR HUB SQL SERVER DATA WAREHOUSE