Oracle allocates Oracle Disk Manager files with contiguous extent layouts for good database performance. When you restore database files they are allocated using these extent attributes. If you are using Oracle RMAN's conventional backup method with any backup software, datafiles are also restored with the proper extent layouts.

If you are using RMAN's "proxy copy" backup method with a backup software other than NetBackup, the extent attributes may not be backed up. To ensure the restored datafiles have proper extent layouts, preallocate the lost datafiles using the odmmkfile command. This command preallocates contiguous space for files prior to restoring them.

For example, to preallocate an Oracle datafile with size 100M, assuming the Oracle database block size is 8K, use the odmmkfile command and enter:

	# /opt/VRTS/bin/odmmkfile -h 8k -s 100m filename

For additional information about the odmmkfile command, see the odmmkfile(1) manual page.