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.
Source:
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
Similar Messages
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Database Smart Flash Cache and Data Guard
We are on Oracle 11.2.0.2 on OEL 5 and our considering buying fusion io (PCIe flash drives) for our Production (Primary) database.
My question is; Can we use Physical Data Guard with the Primary side using Database Smart Flash Cache and keep-ing tables and/or partitions in the Flash Cache and have a Standby side that does not have Database Smart Flash Cache?Yes you can.
Data Guard will not check what type drive you are using. As long as you meet the database and network requirements it will work.
http://www.oracle.com/technetwork/database/features/availability/maa-090890.html
Check out these white papers if you have concerns
"Migration to Automatic Storage Management (ASM)"
"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
mseberg -
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 AMHi;
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 -
I'd like to understand exactly how smart flash cache algorithm works.
I’ve read the Oracle white paper on smart flash cache. It says following:
Exadata Smart Flash Cache provides an automated caching mechanism for frequently-accessed data in the Exadata Database Machine.
What is the algorithm to figure out "frequently accessed data”?
It also say following -
The Oracle Database and Exadata Storage Server Software work closely together to cache frequently accessed data.
When the database sends a read or write request to Exadata Storage Server, it includes additional information in the request about whether the data is likely to be read again and therefore whether it should be cached.
Again what's the algorithm to figure out that data is likely to be read again?
Does it simply cache all random reads against tables and indexes and ignores all sequential reads, scans, writing backups and mirrored blocks?
I’ve also read that, Exadata tags each DB I/O is with metadata indicating I/O type which influence caching . Can somebody shed light on what are various I/O types and which ones are cached?user12254641 wrote:
Thanks for your inputs.
I see it knows what not to cache.
However I was wondering if it has any special algorithm to decide frequently accessed data.
It seems it will cache all random read/writes and of course file headers and control files.There are really two parts to caching: 1) what to cache and 2) the management of cached data.
Assuming cell_flash_cache = default for these segments: index/table, any single block operation is cached. Also IIRC, multi-block reads (but not smart scan multi-block reads) are also cached, up until a certain size (64k or 128K are numbers that comes to mind, but I don't have the code open to check at this moment).
The cache management is basically LRU based, like the db buffer cache -- frequently accessed data is kept on the hot end, and data is aged out on the cold end and replaced.
While I'm sure "algorithms" are interesting for the geek in us, I 'm not sure how this info aids in any management or decision making. Questions are generally better formulated discussing what you would like to do so that appropriate advice can be given. You're question is context free.
Regards,
Greg Rahn | blog | twitter | linkedin -
Pin redo logs into smart flash cache (Exadata Flash PCI F20 cache)
Need to know if we could pin redo logs into smart flash cache.
For example to pin table..
we use Alter table dhaval storage (cell_flash_cache keep) -----
Similarly can we pin redo logs into flash cache ?
If not, what is the alternative to put redo logs into flash cache ?At Oracle OpenWorld the Exadata Smart Flash Log feature was announced. The Smart Flash Log feature requires Exadata Storage 11.2.2.4.0 or later, and Databases version 11.2.0.2 Bundle Patch 11 or greater. This feature allows a modest amount of flash to be used as a secondary write place. It wites redo to both flash and disk and returns the call to the db for the first one that finishes. By doing so it improves user transaction response time, and increases overall database throughput for IO intensive workloads.
Regards,
Greg Rahn
http://structureddata.org -
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?
Danieli 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. -
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 PMExadata 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. -
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
Image version: 11.2.3.2.1.130109
Image activated: 2013-09-24 18:12:52 +0800
Image status: success
System partition on device: /dev/mapper/VGExaDb-LVDbSys1
In our Non-Exadata RAC DBs we use LUNs from Hitachi VSP frame. For very busy DBs like Siebel , we wanted to place our Online Redo logs on high speed disks.
So, our Hitachi SAN admins have allocated LUNs exclusively from Flash Disks within Hitachi VSP frame and we have created Redo Log diskgroup based on these 'Thick provisioned' disks.
This has increased the performance of our RAC DBs significantly.
As I understand, In exadata, you don't have the normal flash disk. Instead, the flash modules are mounted in a PCIexpress card.
In CellCLI> list physicaldisk detail you can see multiple entries like below belonging to the 'flash disk'
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
Although these flash cards can store persistent data because it has battery in it in server goes down, is it actually used to store persistent data.
Smart flash cache is just a caching mechanism for frequently accessed data. Right ? We cannot create diskgroups based on disks from these 'Flash Disks' . Right ?Hi GaryB,
The short answer to your question is: yes, it's possible to use configure flash as permanent storage using "flash griddisks". But in the case of redo logs, it would actually make them perform slower.
The longer explanation: foreground redo writes (the "log file sync" wait event) are very latency sensitive, so it's important for write to be acknowledged as fast as possible. Flash is considerably faster than disk, but not nearly as fast as battery-backed RAM. And Exadata storage servers do have a RAM write cache on their disk controllers. So you will get the best foreground redo write performance from RAM cache write, except when the write cache is full, at which point redo writes need to wait on disk.
Since 11.2.2.4.0 was released in 2012, Exadata has the capability to write redo to _both_ RAM-cached disk and flash memory, and use whichever returns first. So you get the lightning-fast latency of RAM cache unless the cache is full, and worst-case latency is the speed of flash. This capability, smart flash logging, is enabled by default on new Exadata builds; you can check its status by running "view flashlog detail" in CellCLI.
More details in the official whitepaper: http://www.oracle.com/technetwork/database/exadata/exadata-smart-flash-cache-366203.pdf
Hope this helps!
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 AMHi 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 -
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When updating my work's webpage, I cannot seem to get a certain flash component to update. It works fine in IE so I know that it's not on the server's side. I have tried clearing all cache and even private browsing. Nothing I do will cause Firefox to show the updated information. Is there any other way to clear the flash cache other than using Firefox's Clear Recent history feature?
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[help] Flash cache problem?
Operating Environment: IIS6+ASP.Net 2.0+Flash
Framework / Procedure:
When running, Flash will run ASP.NET program. ASP.NET then
extracts data from the database and generates a XML file for Flash.
Flash reads the XML file and parse it into a readable format
for the users.
Problem:
When Flash displays the XML content and user leaves/exits the
webpage, this process creates a change in the database.
Then if this Flash function is executed again, ASP.NET
generates a new XML file, but Flash still displays the old XML
content.
We discovered that when IE's "Temorary Internet Files"
setting is set to AUTO, the above problem would occure, we suspect
this is related to IE cache.
Is there any way to resolve this Flash cache problem?Did you try returning the XML via an ASP script?
In other words have the ASP generate an ASP wrapper that
returns XML.
Then if necessary, you can then add a random URL var to the
Flash XML load url variable. "theXMLWrapper.asx?x=" +
getTimer() -
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 -
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
ChHi 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’
./crsctl start res ora.dbvn.db –p | grep DEPENDENCIES
START_DEPENDENCY=hard(ora.DATA.dg,ora.ARCH.dg,ora.REDO1.dg, ora.REDO2.dg,ora.FLASH1.dg) …
Ch -
Is Flash Cache fully transparent? Can I see content of a flash cache?
Hi,
is there possibility to see content of a flash cache like v$bh ?On the cell layer, you can do
CellCLI> list flashcachecontentThat returns several info about the flashcached objects, amongst others the objectnumber that you can retrieve on the Database Layer with DBA_OBJECTS (object_id there).
AFAIK, there is no direct view on the Database Layer for that.
Kind regards
Uwe Hesse
http://uhesse.wordpress.com
P.S.
Example for looking at multiple Cells for FlashCache info about a certain table:
dcli -g cells.txt "cellcli -e list flashcachecontent attributes cachedKeepSize,cachedSize,hitCount where objectnumber=75698"Usage of dcli as above is explained here:
http://uhesse.wordpress.com/2011/03/22/exadata-part-vi-cell-administration-with-dcli/
Edited by: Uwe Hesse on 22.03.2011 14:22
Added the dcli part -
HP EliteBook Folio 9470m Ultrabook - Flash Cache - Flash Cache
I'm trying to deploy Windows 7 x86 SP1 to an HP EliteBook Folio 9470m Ultrabook with Flash Cache.
I'm using MDT 2010 U1 and running the deployment from USB-media.
Reading the BDD.LOG I can see: "LTI applying image G:\Deploy\Operating Systems\W7 x86 Ent 007\7.wim using SETUP.EXE" and after 18 min "Setup completed successfully." and "LTIApply processing completed successfully." After LTICopyscripts, ZTIConfigure,
ZTIDrivers and ZTINextPhase the computer reboots and I'm getting "Windows boot manager 0xc000000f An error occured while attempting to read the boot configuration data".
When I'm looking at the Boot Config with BCDEDIT.EXE I can see boot manager points at the Flash Cache installed in the machine:
HarddiskVolume3 is the Flash Cache (output from diskpart, list vol):
I've tried to read setupact.log but can't find whats going wrong.
How to handle computers with Flash Cache in deployment with MDT?Machines with more than one physical disk are difficult to deploy to arbitrary disks using technologies like MDT and/or SCCM OSD.
By default you can configure MDT and/or OSD to deploy a task sequence to a specific disk index like Disk(0), but trying to add intelligence to change the target disk is non trivial.
For MDT litetouch you can write a script to change the target disk during the task sequence execution by modifying the OSDDiskIndex variable. So in this example, you could create a script to select the first disk that is larger than 50GB.
Otherwise you are left to deploy to the 1st disk enumerated by the system, which in this case can be the ssd cache disk.
I have written a utility to help modify the OSDDiskIndex using a script.
http://keithga.wordpress.com/2013/09/18/ztiselectbootdisk-wsf/
In the example above I would add the script just before the "format and partition" step in the TAsk sequence. Set a WMI condition for the model of the HP, then add the following to the CS.ini:
[Settings]
Properties=OSBootDiskOverrideWQL
[default]
OSBootDiskOverrideWQL = WHERE Size < 53687091200 and InterfaceType = 'IDE' and MediaType != 'Removable Media'
Keith Garner - Principal Consultant [owner] -
http://DeploymentLive.com
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