An Oracle white paper focuses on what its authors believe are the key Oracle Database 11g capabilities that can help IT departments better optimize their storage infrastructure. Namely:

Manage storage more efficiently

Oracle Database 11g Release 2 introduces the Automatic Storage Management (ASM) Cluster File System (ACFS). ACFS is a POSIX/X-OPEN general-purpose file system for files that are stored outside of the Oracle Database. With ACFS, the functionality of ASM has been extended to all files associated with Oracle Database environments.

Optimize storage performance

Storage Arrays should be sized on the number of I/O Operations per Second, or IOPs they deliver, as well as the achievable MB/s that they can deliver. The total number of IOPs and MB/s required for existing Oracle Databases can be determined from Automated Workload Repository (AWR) reports.

Once the required IOPs or MB/s needed to support the workload have been determined, then the number of disks required in the storage array can be determined. Simply divide the required workload numbers by the specific IOP and MB/s figures obtainable per disk in the storage, and that will determine roughly how many disks are needed for maximum performance.

ASM to maximize I/O bandwidth

With Oracle Database 11g Release 2, frequently accessed data can be striped on the outside of the physical disks, with less frequently accessed data striped on the inside, ensuring frequently accessed data benefits from the faster transfer rates provided by the operational physics of the disks.

According to Oracle, customers that have moved their Oracle Databases from traditional storage arrays to those same environments enabled with ASM have experienced a 25% performance increase in their database, directly attributable to the better I/O balancing enabled by ASM.

Use Direct and Asynchronous I/O to optimize I/O performance

Where supported by the underlying operating system, direct I/O should be generally used with Oracle Database 11g. In addition, Oracle Database 11g also supports asynchronous I/O, where writes performed by the operating system are done asynchronously from the database processes, reducing the potential for bottlenecks caused by I/O waits. Reads can also be done asynchronously as well, including a read-ahead capability for sequential scans, with often-dramatic performance improvements in query intensive workloads.

Use Direct NFS Client to improve Network Attached Storage performance

Oracle Database 11g provides a Direct Network Attached Storage (NAS) client capability that is built directly into the database kernel. This enables direct I/O with the storage devices, bypassing the operating system file cache and reducing the need to copy data between the operating system and Database memory. Direct NFS client also enables asynchronous I/O on NFS appliances.

Use Database Smart Flash Cache to reduce physical disk I/O

Oracle Database 11g Release 2 introduces new Flash PCI cards that can deliver gigabytes of space and support very high numbers of IOPs, often getting close to the I/O characteristics of memory, but at a much lower cost per gigabyte.

Oracle Database can repurpose these cards as a second level cache for data cached in server memory. With the Database Smart Flash Cache feature in Oracle Database 11g Release 2, as data ages out of the memory buffer cache, it s written back to the storage array for long-term data protection. However, at the same time, data blocks are also copied to available space on flash cards. The next time these data blocks are required in the database buffer cache, they are retrieved from the Smart Flash Cache, avoiding the need to perform any physical I/O from the storage array. Using the PCI Express interface also means that these I/O operations bypass any disk controller overhead.

Sun Oracle Exadata Storage Servers

The above techniques, which are detailed in the 22-page white paper, all optimize the performance of existing storage arrays. However the new storage solution - Sun Oracle Exadata Storage Server - may be more along the lines of what some customers may want to optimize their storage environments. General details are provided.

Compression

Compression is one of the major enablers of efficient storage management, and Oracle Database 11g provides many multiple techniques for effective data compression:

• Basic Compression: Read only tables and partitions in Data Warehouse environments or “inactive” data partitions in OLTP environments.

• OLTP Compression: Active tables and partitions in OLTP and Data Warehouse environments.

• SecureFiles Compression: Non-relational data in OLTP and Data Warehouse environments.

• Index Compression: Indexes on tables in OLTP and Data Warehouse environments.

• Backup Compression: All environments.

• Hybrid Columnar Compression, Data Warehousing: Read only tables and partitions in Data Warehouse environments.

• Hybrid Columnar Compression, Archival: “Inactive” data partitions in OLTP and Data Warehousing environments.

Protecting against data loss

• Corruption: Oracle Database has comprehensive built-in checks to detect and repair data corruptions. Using a single parameter set to a desired protection level, the Oracle Database can detect corruptions in data and redo blocks using checksum validation, detect data block corruptions using semantic checks, and detect writes acknowledged, but actually lost by the I/O subsystem.

• ASM Mirroring: ASM uses a unique mirroring algorithm that mirrors extents. When ASM allocates a primary extent of a file to one disk in a failure group, it allocates a mirror copy of that extent to another disk in another failure group, ensuring that a primary extent and its mirror copy never reside in the same failure group. Unlike other volume managers, ASM has no concept of a primary disk or a mirrored disk, a disk group only requires spare capacity; a hot spare disk is unnecessary.

• Backup and restore: Oracle Database 11g supports many tape backup and vaulting environments through the Oracle Backup Solutions Program, a cooperative program designed to facilitate tighter integration between Oracle's backup products and those of third-party media management vendors. This white paper touches on Oracle Secure Backup, Fast Recovery Areas and Incremental Backups, and Read only Tables and Tablespaces.

• Human Error: Oracle Database 11g provides unique flashback capabilities. Flashback allows operations that were inadvertently performed online to be undone online.

• Disaster: The Oracle Database works with remotely mirrored storage solutions, however, there is also a built-in standby solution, called Oracle Data Guard. This solution only transmits the writes to the redo logs from the production databases to the standby databases. This can mean a 1/7th reduction on the network of the volume, and up to 1/27th of I/O operations allowing a much smaller capacity network to be utilized between the data centers. Also, network latency is less of an issue, allowing synchronous operations to be used across the network.

"Many IT organizations today use inefficient storage management techniques underneath their Oracle Databases that are based on traditional practices that are no longer the industry’s best operating procedure," the paper concludes. "By re-evaluating and using many of the advanced capabilities provided for storage optimization by the Oracle Database, IT professionals can reduce their overall storage costs by a factor of 10x."

More Information

Optimizing and Protecting Storage with Oracle Database 11g Release 2 - Oracle white paper

Free eBook: Guide to Oracle 11g and Database Migration

Oracle Database 11g Release 2

Exadata Hybrid Columnar Compression (EHCC)

Sun Oracle Database Machine and Exadata Storage Server

What's New in Oracle Exadata V2? [...read more...]

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