Oracle database smart flash cache

Oracle database
Smart Flash Cache
Johan Louwers
Johan.Louwers@capgemini.com

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 and Flash Cache | JAN-2014 | Johan Louwers
Copyright ©2013 Capgemini. All Rights Reserved

2

Oracle Database – SGA Memory Architecture
 SGA (System Global Area)
• Java Pool
• Shared Pool
• Redo Buffer
• Large Pool
• Streams Pool
• Buffer Cache


3

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.


4

A) Storage read
•


•

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.


5

A) Storage read
•


•

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.

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.


6

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.


7

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


8

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


9



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.


10



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


11

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:
Johan.Louwers@capgemini.com
@johanlouwers
@CapgeminiOracle
http://johanlouwers.blogspot.com
http://www.capgemini.com/experts/
oracle-and-cloud-computing/johanlouwers


12

About Capgemini
With more than 130,000 people in 44 countries, Capgemini is one
of the world's foremost providers of consulting, technology and
outsourcing services. The Group reported 2012 global revenues
of EUR 10.3 billion.
Together with its clients, Capgemini creates and delivers
business and technology solutions that fit their needs and drive
the
results
they
want.
A
deeply
multicultural
organization, Capgemini has developed its own way of
working, the Collaborative Business Experience™, and draws on
Rightshore®, its worldwide delivery model.
Learn more about us at www.capgemini.com.

www.capgemini.com
The information contained in this presentation is proprietary.
Copyright © 2013 Capgemini. All rights reserved.
Rightshore® is a trademark belonging to Capgemini.

Oracle database smart flash cache

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