VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Using Oracle RMAN to Back Up and Restore Oracle Disk Manager Files Prerelease 8 September 2005, 8:55am
498 VERITAS Storage Foundation for Oracle Administrator’s Guide
Using Oracle RMAN to Back Up and Restore Oracle Disk
Manager Files
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. Refer to the odmmkfile(1)
manual page for more information.
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