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Just as with CEOs demanding faster reports, sometimes availability is defined more by a human resource issue than actual data availability. At Horatio's Woodscrews, they run all their production systems on Solaris, but are investigating Linux as an alternative. The first step of the investigation is to set up the test and development shop with Linux servers, and then move a copy of production data to the new Linux servers for application testing.
Sometimes availability has as much to do with user perception as it does with database reality. When upper management complains, even brand new DBAs must take measures to improve performance for them. In this situation, the HA DBA will be best served by looking to reformulate some of the tables used by his boss, or by creating materialized views to subset the data appropriately. This is covered in Chapter 2, in the section 'Materialized Views.'
Availability isn't always about the production database, and an outage may simply be defined by 'idle developers twiddling their thumbs.' But a move of database information to a new platform has always been a huge undertaking involving the tried and true export and import utilities to logically extract data. However, this always came with huge resource issues at the export database.
Starting in Oracle Database 10g, Oracle has built in a means of using the Transportable Tablespace feature of the database and allowing it to transfer tablespaces across platforms. This is discussed in Chapter 2, in the section 'Transportable Tablespaces.'
The Linux servers arrived late in the week, and were configured with the Oracle software image over the weekend. On Monday, the development lead needs to get the data moved from the production Woodscrew database to the Linux servers. So the development lead contacts the senior DBA for the database and asks that they transition the data to the new Linux servers.
The dilemma for the DBA is that getting a read-consistent view of the Woodscrew tables is nearly impossible for long enough to get an export to complete. The only time there is a large enough window for such an operation would be the following weekend. The backups cannot be used, because they are backups of Solaris datafiles. But if they wait for the weekend, the development team will sit idle all week on a project that has imminent deadlines. How can they get the data moved across platforms in an expedient way?
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