Best Practices When Using dataxform
The dataxform utility transforms files in place, overwriting file blocks as it transforms them. In-place transformation is advantageous, because it minimizes the temporary storage required to transform large file sets. However, if dataxform fails partway through, files being transformed at the moment of failure must be restored from backups after the run is complete and access to the data set has been re-enabled. This implies that a reliable, up-to-date backup copy of a protected file set is a necessary prerequisite to in-place transformation.
If a large file set must be fully backed up prior to running dataxform, backup time must be added to the estimated transformation time to calculate the window of unavailability. (Backup and transformation must be consecutive so that files do not change between the two.) For large data sets, backup time can be substantial. In no case, however, can one recommend bypassing the backup step. If files are worth protecting with CTE, they are presumably of significant value to the enterprise. Therefore, every reasonable effort must be made to protect them against loss as well as theft.
