Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

Because Quick I/O files are treated as raw devices, the Quick I/O file must exist
and have the necessary space preallocated to it before the file is restored using
RMAN. Space can be preallocated to the file when the file is created using the
qiomkfile command. In this case, the file can be restored using RMAN with no
other special handling, and the file can be accessed after the restore as a
Quick I/O file:
■ If both the Quick I/O link name and the hidden file are missing, use qiomkfile
to preallocate and set up the Quick I/O file.
■ If either the Quick I/O link name or the hidden file alone exist, delete these
files and recreate the Quick I/O file of the required size using qiomkfile.
■ If both the Quick I/O link name and the hidden file are intact, you may proceed
to restoring the file.
■ If you attempt to restore a Quick I/O file and the original is smaller than the
required size, the restore will fail with an Oracle error ORA-27069 (I/O attempt
beyond the range of the file). The failure results because Quick I/O does not
allow extending writes (in other words, attempts to increase the size of a file
by writing beyond the end of the file). This same behavior is encountered when
attempting to restore Oracle datafiles built on raw devices. If the restore fails
with the above error, delete the Quick I/O link and its hidden file, then recreate
or extend the file using qiomkfile.
Note: The space needed for the Oracle datafile is the size of the datafile plus
one Oracle block (as specified by the init.ora parameter, db_block_size).
About backing up and restoring Oracle Disk Manager
files using Oracle RMAN
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.
Using third-party software to back up files
About backing up and restoring Oracle Disk Manager files using Oracle RMAN
394