11.2 Flash Cache feature

I an 11.2 RAC database running.
I tried to enable Flash Cache
db_flash_cache_file
db_flash_cache_size
when I tried to start the database i get these errors
ORA-00439: feature not enabled: Server Flash Cache
ORA-01078: failure in processing system parameters
Does anyone know how to enable the feature?
Daniel

i wonder if Oracle is using ordinary SSD in Exadata Storage Cell to enable the smart flash cache feature. Has anybody seen an Exadata V2 and can report if there are SATA/SAS - SSDs with an ordinary hard disk controller build into the storage cell or if they do it a somehow other way. All i have read is that these flash devices are not filled by a LRU algorithm. I am really interested in technical details.http://www.oracle.com/technology/products/bi/db/exadata/pdf/exadata-technical-whitepaper.pdf
Each Exadata cell comes with 384 GB of Exadata Smart Flash Cache. This solid state storage delivers dramatic performance advantages with Exadata storage. It provides a ten-fold improvement in response time for reads over regular disk; a hundred-fold improvement in IOPS for reads over regular disk; and is a less expensive higher capacity alternative to memory. Overall it delivers a ten-fold increase performing a blended average of read and write operations.
The Exadata Smart Flash Cache manages active data from regular disks in the Exadata cell – but it is not managed in a simple Least Recently Used (LRU) fashion. The Exadata Storage Server Software in cooperation with the Oracle Database keeps track of data access patterns and knows what and how to cache data and avoid polluting the cache. This functionality is all managed automatically and does not require manual tuning. If there are specific tables or indexes that are known to be key to the performance of a database application they can optionally be identified and pinned in cache.There look to be two important advantages over regular SSD attached to an Oracle database here: that the caching is in combination with the Oracle Database (not just LRU, just as you point out yourself), but also that the storage cell's SmartScan technology will only project the required rows and columns to the database server so that higher effective bandwidths are achieved.

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11gR2 Vs Exadata- Flash Cache performance

Flash Cache feature is available in both 11gR2 & Exadata. The difference being in 11gR2 it is an extension of the database buffer, however in Exadata it is a separate hardware component in the storage server.
Apart from this, I would like to know how the Exadata Smart Flash Cache is superior to the 11gR2 flash cache? Is it that the 11gR2 flash cache is not "smart" and ends up caching data that is not useful in terms of caching.
The 11gR2 oracle documentation does not seem to mention anything about this flash cache feature. Any idea?
Edited by: museshad on Jun 8, 2011 2:13 PM

Exadata Smart Flash Cache and Database Smart Flash Cache use SSD advantages.
On Exadata, We don't need to change anything in Database (database machine). We just "create flashcache" on cell. and Exadata Environment not support 11gR2 feature (Database Smart Flash Cache), Because it has Exadata Smart Flash Cache.
http://surachartopun.com/2011/02/how-to-use-exadata-smart-flash-cache.html
On 11gR2 (none Exadata) and have flash disk, we can use Database Smart Flash Cache, We have to change 2 initialization parameters on database.
db_flash_cache_file
db_flash_cache_size
http://surachartopun.com/2010/02/oracle-11gr2-flash-cache.html
Flash Cache feature is available in both 11gR2 & Exadata. On Exadata, we use Exadata SMart Flash Cache.
On None Exadata, we use database smart flash cache.
*** Exadata Environment not support 11gR2 feature (Database Smart Flash Cache) ***
The difference being in 11gR2 it is an extension of the database buffer, however in Exadata it is a separate hardware component in the storage server.when we get data, we read from disks to database buffer, when blocks are evicted from database buffers, they are stored in flash cache. After that ... someone get data again -> oracle read in database buffer cache, if not found, then oracle read in flash cache(if not found, oracle read from disks)
read more:
http://www.oracle.com/technetwork/articles/systems-hardware-architecture/oracle-db-smart-flash-cache-175588.pdf
http://www.oracle.com/technetwork/middleware/bi-foundation/exadata-smart-flash-cache-twp-v5-1-128560.pdf
Apart from this, I would like to know how the Exadata Smart Flash Cache is superior to the 11gR2 flash cache? Is it that the 11gR2 flash cache is not "smart" and ends up caching data that is not useful in terms of caching.read 2 above whitepapers.

Smart flash cache and Oracle Linux 6

I can't use smart flash cache feature on Oracle database 11.2.0.3.0 I installed on Oracle Linux 6.
I installed Oracle database 11.2.0.3.0 on Oracle Linux 6.1 and try to use smart flash cache feature,
I got this error when I start database:
ORA-00439: feature not enabled: Server Flash Cache
ORA-01078: failure in processing system parameters
My environment are:
OS: Oracle Linux 6.1 (x86_64)
Kernel: 2.6.32-100.34.1.el6uek.x86_64
DB: 11.2.0.3.0
Related parameter in pfile I used to start database to use smart flash cache feature,
*.db_flash_cache_file='/d09/db_flash_cache/db_flash_file.raw'
*.db_flash_cache_size=32G
I have accomplished this on Oracle database 11.2.0.2.0 on Oracle Linux 5.5 before, I don't think new version of database cause the issue but I'm not sure is there any smart flash cache issue with the Oracle Linux 6.1?
Note:
I need to use Oracle Linux 6.1 instead of Oracle Linux 6.2 and can't updated the kernel to UEK2 because the SSD PCI-E card only support on this distro and kernel version.
Edited by: Rapid E-Suite on Apr 16, 2012 11:22 AM

Hi;
Oracle Enterprise Linux was changed to Oracle Linux, isn't ?
Oracle stopped calling their Linux distro as "Oracle Enterprise Linux" since OEL5.5 or 5.6 (I'm not sure). Therefore, today there is Oracle Linux only? If so, I'm using OL6.1 also means OEL6.1, correct?
But, If the doc really means Oracle Enterprise Linux only then should it means OEL5.5 or 5.6?AFAIK both refer to Oracle Linux.If somebody mention they have OEL6.1 or Oracle linux 6.1 than I accept it Oracle linux(Enterprise)
You may see FAQ documents:
http://www.oracle.com/us/technologies/027617.pdf?ssSourceSiteId=ocomtr
If you have still dubt than I suggest rise thread at Forum Home » Linux » Oracle Linux forum part
Regard
Helios

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http://www.oracle.com/technetwork/database/features/availability/maa-090890.html
Check out these white papers if you have concerns
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"Best Practices for Creating a Low-Cost Storage Grid for Oracle Databases"
In addition here's an example of using two different file systems with Data Guard
http://pythianpang.wordpress.com/2009/07/07/data-guard-asm-primary-to-filesystem-physical-standby-using-rman-duplicate/
Best Regards
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Iniitialising flash cache parameters

Hi could someone please help me to set up flash cache.,..
I have OEl 5.5 installed and patched.
I have my SSD mounted..
but when i ran the command 'alter system set db_flash_cache_file ='/media/ssd/' scope=spfile;'
.... I totally messed up my database, and It wouldn't startup giving ORA-01078: failure in processing system parameters...
I have now fixed this and am back to square one ...
Could someone plzzzz help me set up the initialisation params?

The Database - General or Installation might be a better forum to place this question.
General Database Discussions
There is too little information to analyze the problem. Do you have more info in the alert_log file? Did you also receive a ORA-00439: feature not enabled: Server Flash Cache error? Is your platform and storage supported?
Here are some links that could help you to solve the problem:
http://guyharrison.squarespace.com/blog/2009/11/24/using-the-oracle-11gr2-database-flash-cache.html
Edited by: Markus Waldorf on Aug 11, 2010 5:55 PM
I just found your other post
Re: flash cache initialization parameters
so this one seems obsolete.
Edited by: Markus Waldorf on Aug 11, 2010 6:13 PM

Smart Flash Cache

Hi,
is the smart flash cache only available on sun oracle hardware ?
I know that this option is available only on OEL end Solaris, but I'n not sure on hardware ?
Thank a lot.

Hi;
Oracle Database Smart Flash Cache is a feature that was first introduced with Oracle Database 11g Release 2. Only available on Oracle Linux and Oracle Solaris, this feature increases the size of the database buffer cache without having to add RAM to the system. In effect, it acts as a second level cache on flash memory and will especially benefit read-intensive database applications.
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http://blogs.oracle.com/linux/entry/oracle_database_smart_flash_cache_only_on_oracle_linux_and_oracle_solaris
Also see:
How To Size the Database Smart Flash Cache [ID 1317950.1]
Regard
Helios

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johnpau2013 wrote:
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Flash Cache is not Flash Disk. Right ?

Hardware: X3 - Half Rack
# imageinfo
Kernel version: 2.6.32-400.11.1.el5uek #1 SMP Thu Nov 22 03:29:09 PST 2012 x86_64
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          name:                   FLASH_1_0
         diskType:               FlashDisk
         luns:                   1_0
         makeModel:              "Sun Flash Accelerator F40 PCIe Card"
         physicalFirmware:       UI39
         physicalInsertTime:     2013-09-13T17:56:10+08:00
         physicalSerial:         5L0066Y5
         physicalSize:           93.13225793838501G
         slotNumber:             "PCI Slot: 1; FDOM: 0"
         status:                 normal
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Hi GaryB,
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Marc

Need RAC/ASM multinode flash cache configuration advice

We have a working two-node RAC database. We are installing a new 640gb fusion flash card in each node. The card is a double-card, so that it shows up as two devices: /dev/fioa and /dev/fiob on each node.
We have created two private disk groups, one on each node. The disk group on node 1 is "+FLASHCACHE" and the disk group on node 2 is "+FLASHCACHE2".
We haven't found any specific examples of how to configure the init parameters for flashcache on RAC/ASM. We are guessing that we should do the following. If someone would critique and confirm or suggest something different, we would appreciate it very much!
prod1.db_flash_cache_file='+FLASHCACHE/flash1'
prod2.dg_flash_cache_file='+FLASHCACHE2/flash2'
*.db_flash_cache_size=600G
Thanks for any advice.
Jim
Edited by: jimbev90 on Jan 5, 2012 8:18 AM

Hi Jim,
prod1.db_flash_cache_file='+FLASHCACHE/flash1'
prod2.dg_flash_cache_file='+FLASHCACHE2/flash2'
*.db_flash_cache_size=600GYour configuration is correct.
Database Smart Flash Cache is not shared across RAC nodes; it is private to each RAC instance. For that reason, each RAC instance must define its own local flash cache file path. When the flash cache is managed by ASM, a separate diskgroup is needed for the flash cache of each instance.
You can use ALTER SYSTEM to set db_flash_cache_size to zero to disable the flash cache. You can also use ALTER SYSTEM to set the flash cache back to its original size to reenable it.
Read this white paper Oracle Database Smart Flash Cache
http://www.oracle.com/technetwork/articles/systems-hardware-architecture/oracle-db-smart-flash-cache-175588.pdf
Regards,
Levi Pereira

Db flash cache file on ASM for RAC

Dear guys/gurus,
I am installing RAC 11.2 on Solaris 10 sparc. After RAC intallation finish i want to do the db flash cache.
On each node, i have 4 SSD Disk and want to create 2 diskgroup FLASH1 on node1 and FLASH2 on node2 for db_flash_cache_file
inst1.db_flash_cache_file=+FLASH1/flashfile01
inst2.db_flash_cache_file=+FLASH2/flashfile02
The question is, in RAC how can i create a local diskgroup example FLASH1 is only mount on node1 and the same for FLASH2. Because when the database startup it try to mount FLASH1 on both node, also FLASH2 and thrown an error if node 2 can not see +FLASH1.
Please advise, So thanks and best regards
Ch

Hi Sharma,
RAC and DB version is 11.2.0.2. Yes, as you said, it may involved in hard dependency
When i start db the error come : Unable to start ‘ora.dbvn.db’ because it has a ‘hard’ dependency on ‘ora.FLASH1.dg’
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START_DEPENDENCY=hard(ora.DATA.dg,ora.ARCH.dg,ora.REDO1.dg, ora.REDO2.dg,ora.FLASH1.dg) …
Ch

11.2 Flash Cache feature

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