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Delphix

What is DoubleSync?

Issue

Initial load of a dSource can sometimes take several hours/days, and to be provisionable it also requires to apply hours/days of archived logs, which makes the resulting Snapshot almost unusable; as a workaround an immediate manual second Snapshot is taken that only takes minutes/hours, and is therefore usable as a provisionable point for virtual databases (VDBs).

This is also useful when switching the dSource to use BCT or if a SnapSync has not been performed for some amount of time.

Resolution

In Delphix version 4.3.x using the CLI, it is possible to request during Linking that a doubleSync is performed if linkNow is set to true. 
When the doubleSync option is selected, two SnapSyncs in a row are run, the first one will not even bother to get the archived logs to make the first Snapshot consistent. This means that LogSync will not run during the first SnapSync, or if LogSync is not enabled, the archived logs after the backup of the data will not be retrieved. Once the first SnapSync finishes a second SnapSync is started, starting LogSync if enabled, or taking an archived log backup after the data files have been backed up.
The doubleSync option is also available for manually initiated SnapSync, but it is only available through the CLI, just like forceFullBackup option. As a forceFullBackup is similar to an initial load, doubleSync makes a great companion to forceFullBackup, although it is not needed to use both at the same time.

Instructions for linking with doubleSync:

ssh delphix_admin@your engine
delphix > database
delphix database > link
delphix database link*> edit source.operations
delphix database link*> edit postSync
delphix database link*> add
delphix database link*> set command=""
delphix database link*> back; back
delphix database link*> edit preSync
delphix database link*> add
delphix database link*> set command=""
delphix database link*> back; back; back
delphix database link*> set source.config=XXXX
delphix database link*> set container.name=XXXX
delphix database link*> set container.group=XXXX
delphix database link*> set container.sourcingPolicy.logsyncEnabled=true
delphix database link*> set container.sourcingPolicy.logsyncMode=ARCHIVE_REDO_MODE
delphix database link*> set linkNow=true
delphix database link*> set doubleSync=true
delphix database link*> set dbUser=XXXX
delphix database link*> set environmentUser=XXXX
delphix database link*> set dbCredentials.password=XXXX
delphix database link*>commit

Instructions for syncing with doubleSync:

ssh delphix_admin@yourengine
delphix > database
delphix database > select XXXX
delphix database "XXXX"> sync
delphix database "XXXX"sync *> set doubleSync=true
delphix database "XXXX"sync *>commit

Additional Information

If a doubleSync is suspended (only initial load can be suspended), doubleSync is lost on resume. In this case, the best thing to do is start a new sync with doubleSync=true. Files already backed up by the first job will not be backed up again, only the new files will be backed up. Also if a forceFullBackup with doubleSync, (i.e. non-initial syncs) is stopped both values are lost, so the next job must set them again, please note that forceFullBackup will backup all the datafiles already backed up during the previously run job.

As of 5.0 there is support for doubleSync in the GUI. GUI support is only available for the initial sync, and is visible on the “Advanced” option in “Data Management” tab of the dSource wizard. 

As of 5.1 doubleSync is not lost on resume.