Databases Reference
In-Depth Information
Not
■
on exadata Compute nodes, it is not common for high rates of change on your active
/
and
/u01
file systems.
typically, trace files, audit files, and other log files are your most actively created or changed files. knowing this, your
snapshot volumes probably do not need to be sized very large; in this recipe, we sized the
root_snap
volume at 1 GB and
the
u01_snap volume
at 5 GB.
In the example in this recipe, as stated in the Solution section, we created an additional physical volume called
backup
and mounted this to
/mnt/backup
. This task by itself was not directly related to LVM snapshots; we simply
created this volume to back up the contents of our active file systems to.
Not
■
please see recipe 8-11 to learn how to restore your compute nodes from LvM snapshot backups.
8-6. Backing Up Your Oracle Databases with RMAN
Problem
You want to back up your Oracle databases running on Exadata.
Solution
Oracle databases on Exadata use Oracle Automatic Storage Management (ASM). Oracle Recovery Manager, or RMAN,
is the only supported means to create restorable backup copies of ASM data files and, as such, RMAN must be part of
your backup strategy on Exadata if you plan on backing up your database.
How It Works
On Oracle Exadata, if you wish to back up your Oracle databases, you must use Oracle RMAN because the
database files will reside on Oracle ASM storage. Using RMAN with Oracle backups is a lengthy topic and deserves
a complete text in and of itself. As such, this recipe only scratches the surface of Oracle RMAN's functionality and
usage. To learn more about Oracle RMAN, please consult the product documentation at
Optimizing your Oracle RMAN backups starts by understanding the physical capabilities of your Exadata
Compute Nodes, storage cells, and network components. When backing up internal to Exadata using your Fast
Recovery Area, Oracle has benchmarked up to 3 TB/hour for an Eighth Rack, 5 TB/hour for a Quarter Rack,
8-9 TB/hour for a Half Rack, and between 17 and 18 TB/hour for an Exadata Full Rack using full RMAN image copies.
Incremental backups, in each case, will achieve even faster results depending on your workload.
Following are a series of recommendations based on our experience in the field on a number of RMAN backup
topics for Exadata:
•
If you can justify the disk space requirement, perform RMAN backups to Exadata using the
Fast Recovery Area (FRA). This will provide the highest performance, lead to the highest
performing recovery times, and provide the greatest amount of flexibility in your recovery
scenarios.
•
When backing up to the FRA, perform an RMAN Level 0 backup once per week and
incremental backups on the other six days.
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