Oracle ZFS Storage Appliance Administration Manual page 633

_backup_file_bufsz - Size of the buffers used to process image copies
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For backup and restore operations on backup sets and image copies, set the number of buffers to
64 and the buffer size to 1 MB:
SQL> alter system set "_backup_disk_bufcnt"=64;
SQL> alter system set "_backup_file_bufcnt"=64;
SQL> alter system set "_backup_disk_bufsz"=1048576;
SQL> alter system set "_backup_file_bufsz"=1048576;
These commands may be configured persistently by adding them to the SPFILE, or they may
be set dynamically in the Oracle RMAN run block used to execute the backup or restore
operations.
The following code fragments show how to dynamically tune the buffer sizes and counts for
backup and restore operations.
Backup set backup:
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run
{<br/>
sql 'alter system set "_backup_disk_bufcnt"=64';<br/>
sql 'alter system set "_backup_disk_bufsz"=1048576';<br/>
allocate channel...
...<br/>
backup as backupset database;
}
Backup set restore:
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run
{<br/>
sql 'alter system set "_backup_disk_bufcnt"=64';<br/>
sql 'alter system set "_backup_disk_bufsz"=1048576';<br/>
allocate channel...
...<br/>
restore database;
}
Image copy backup:
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run
{<br/>
sql 'alter system set "_backup_file_bufcnt"=64';<br/>
Configuring Oracle Direct NFS (dNFS)
Integration 633