Re: Exadata Cacheflash Compression

From: Craig Dickman <craig_dickman_at_yahoo.com>
Date: Thu, 8 May 2014 08:26:35 -0700 (PDT)
Message-ID: <1399562795.5885.YahooMailNeo_at_web163803.mail.gq1.yahoo.com>


Here's how I understand it.  The data in flashcache is compressed by default anyway, it happens automatically.  Prior to X4, the data in the flashcache would get compressed but the extra space made available by this compression was not usable.  

With the release of X4, Oracle gives you the ability to enable flashcache compression which essentially gives you the ability to use the space freed up by the automatic flashcache compression.  Basically, you turn 20TB of flash cache into 40TB usable if you have Advanced Compression.


________________________________
 From: Thomas P S <dmarc-noreply_at_freelists.org>
To: ORACLE- L <oracle-l_at_freelists.org>; Roy <royxavier_at_yahoo.com> 
Sent: Thursday, May 8, 2014 6:29 AM
Subject: Exadata Cacheflash Compression
 


Dear List,

We have X4-2 Half Rack with 20TB flash cache with database size 8TB.  I am very reluctant to enable flashcache compression as the size of the database is half of flashcache, but Oracle says enabling flashcache compression is a best practice.  Every code execution need time, even though FC is implemented in hardware level compression, still I believe, there will be a penalty.  In this scenario, enabling flashcache compression is a wise idea?   Any one got  falshcache I/O performance test results with compression and with out? 

Note: License is not an issue as we have Advanced Compression license.

Thanks in advance,

Thomas Saviour
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Received on Thu May 08 2014 - 17:26:35 CEST

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