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Best Practices for Oracle 11g Backup and Recovery using RMAN and Dell EqualLogic Snapshots

8 Best practices for backup and recovery

8.1 Use a Virtualized Database Backup Server

We recommend that you use Dell EqualLogic Snapshots along with Oracle RMAN to reduce

performance impact on production database servers (CPU Utilization) and improve the efficiency of

backup and recovery operations. The EqualLogic snapshot feature allows you to offload the entire

RMAN backup copy operation to a dedicated host system, thus allowing you to free up critical

production database server CPU resources for mission-critical tasks.

If using VMware ESX to host database servers, use the Virtual NIC Type and enable jumbo frames

We used the guest OS iSCSI initiators. Virtual NICs were created using the “VMXNET3” type. VMXNET3

type NICs support jumbo frames. Jumbo frames should be enabled on the NICs on the Guest OS and

also on the vSwitch used for iSCSI SAN connectivity. Use the following command to verify that jumbo

frames are enabled end-to-end from Guest OS to Storage array:

ping –s 8900 –M do <Storage_Array_IP>

We recommend installing the latest version of VMware tools on the guest OS.

8.2 RMAN backup

The Flash recovery area is a key component that is tightly integrated with Oracle’s RMAN utility for

performing disk-to-disk backup. The flash recovery area allows DBAs to create a location on the disk

where the database backup and recovery-related files can easily be managed. Below are some key

best practices when using the RMAN backup utility:

• Separate the flash recovery area from the database volumes (data files and redo log files).

During the testing detailed in this paper, the PS6010E array hosting the archive logs and

backup data was placed in a different EqualLogic pool.

• The flash recovery area can be configured using lower-cost, high-capacity storage. In our test

configuration, the flash recovery area used a PS6010E array consisting of 7.2K SATA drives.

• Distribute the backup I/O across multiple volumes to achieve better performance. We

distributed the flashback recovery area across five volumes in the EqualLogic pool.

• Use multiple ASM disks to help distribute the I/O across Oracle ASM disks. During the test suite

detailed in this paper, we distributed the backup I/O across five ASM disk groups.

8.3 Snapshot reserve space sizing

Typically, database administrators will keep at least two snapshots per day in order to reduce mean

time to recovery (MTTR). Disk consumption by EqualLogic snapshots only grows when data changes

in the volume. You should monitor snapshot reserve space utilization. EqualLogic snapshot reserve

space utilization will depend on:

• Frequency of snapshots and the number of snapshots that need to be retained

• The rate of data change in the database volumes that retain snapshots