oracle database smart flash cache

Oracle database Smart Flash CacheJohan [email protected]

2Copyright ©2013 Capgemini. All Rights Reserved

Oracle Database and Flash Cache | JAN-2014 | Johan Louwers

Oracle Database – Smart Flash Cache

Database Smart Flash Cache. This feature is available on Solaris and Oracle Enterprise Linux and allows customers to increase the effective size of the Oracle database buffer cache without adding more main memory to the system. For transaction-based workloads, Oracle database blocks are normally loaded into a dedicated shared memory area in main memory called the System Global Area (SGA). Database Smart Flash Cache allows the database buffer cache to be expanded beyond the SGA in main memory to a second level cache on flash memory.



Oracle Database – SGA Memory Architecture

SGA (System Global Area)• Java Pool

• Shared Pool

• Redo Buffer

• Large Pool

• Streams Pool

• Buffer Cache



Oracle Database – Flash Cache Lifecycle

A) Storage read• When a block is retrieved from the storage it is stored

within the buffer cache of the system global area.

• When the block is deemed no longer needed it is, traditionally, removed from the buffer cache and a new call to the storage is done when it is needed again.







B) Flash cache write• When using Smart Flash Cache a block is not removed

from the buffer cache however is evicted to the flash cache instead.







B) Flash cache write• When using Smart Flash Cache a block is not removed

from the buffer cache however is evicted to the flash cache instead.

C) Flash cache read• When a block is needed again and is not available in the

buffer cache in the SGA it is retrieved (if available) from the flash cache instead.

• If a block is not available in the SGA buffer cache AND it is not available in the flash cache, only then a call to the storage is done.



Oracle Database – Flash Cache Advantages

Advantages• By limiting the number of IO calls to the storage the overall

performance of your database is extremely improved.

• By limiting the load on your shared storage not only this specific database benefits, all databases and applications that make use benefit due to a lower overall load on the shared storage.



Oracle Database – Flash Cache Hardware

Available hardware• Flash Cache is (in general) offered via one or more PCIe

cards that are seen by the operating system as a separate device. A growing number of vendors are in the market



Oracle Database – Flash Cache Implementation

Operating system considerations• Generally speaking ALL PCIe flash cards will work on

almost every popular operating system including MS Windows, Linux and Solaris.

• The database functions used to make use of the Oracle database Flash Cache will ONLY work on Oracle Linux and Oracle Solaris and not on any other operating system




Operating system device• Generally a flash card will be showing as a device in /dev/

on your operating system.

• Example of a EMC VFcache controller card on Linux:

• Example of a EMC Vfcache card drive representation on Linux

• Depending on the make and model of your card you will have to follow the specific instructions of the vendor to ensure the card is installed on your system in the correct manner.




Oracle Database implementation• DB_FLASH_CACHE_FILE

– Should point to the location(s) of the flash device(s) to be used.

• DB_FLASH_CACHE_SIZE

– Should state the size (per location) that can be used for flash cache.

db_flash_cache_file = /dev/raw/sda, /dev/raw/sdb, /dev/raw/sdc db_flash_cache_size = 32G, 32G, 64G



About – Johan Louwers

Johan Louwers - Oracle and Cloud Computing

I am spearheading innovation within the Capgemini Group by developing the ‘Capgemini Oracle Run’ hosting and computing cloud and ensuring our clients have a completely managed enterprise IT environment.

Capgemini Expert on:

• Infrastructure Transformation • Cloud Computing• Oracle Technology

Contact me:

[email protected]

@johanlouwers

@CapgeminiOracle

http://johanlouwers.blogspot.com

http://www.capgemini.com/experts/oracle-and-cloud-computing/johan-louwers

The information contained in this presentation is proprietary.Copyright © 2013 Capgemini. All rights reserved.

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