Re: Exadata Cacheflash Compression
From: Thomas P S <royxavier_at_yahoo.com>
Date: Fri, 9 May 2014 20:30:45 -0700 (PDT)
Message-ID: <1399692645.18779.YahooMailNeo_at_web162405.mail.bf1.yahoo.com>
Date: Fri, 9 May 2014 20:30:45 -0700 (PDT)
Message-ID: <1399692645.18779.YahooMailNeo_at_web162405.mail.bf1.yahoo.com>
Thanks Carol, Craig, Gopal and George for sharing. I will be setting up compression (x - 2) next week. Thanks, Thomas On Friday, May 9, 2014 8:14 PM, Carol Dacko <dackoc_at_gmail.com> wrote: This works for me: cellcli -e list cell detail | grep flashCacheCompress flashCacheCompress: TRUE And if you follow the directions in the note, you will actually see the difference in size like: This is on an X3-2: cellcli -e list flashcache detail | grep effectiveCacheSize effectiveCacheSize: 1488.75G And after enabling the compression: cellcli -e list flashcache detail | grep effectiveCacheSize effectiveCacheSize: 2978.75G Hope this helps your understanding! Carol Dacko Enkitec On Fri, May 9, 2014 at 10:20 AM, K Gopalakrishnan <kaygopal_at_gmail.com> wrote: Tom, > > >Try CELLCLI list flashcache attributes all. > > >-Gopal > > > > > > > >On Fri, May 9, 2014 at 8:37 AM, Thomas P S <dmarc-noreply_at_freelists.org> wrote: > >That made me to ask one more question: The above MOC Doc saying >> >> >>Flash cache compression dynamically increases the logical capacity of the flash cache by transparently compressing user data as it is loaded into the flash cache. This allows much more data to be kept in flash, and decreases the need to access data on disk drives. >> >> >> >>So, it is increasing the logical capacity of the flash cache by transparently compressing the user data and never said the capacity is getting doubled. So, are we really right to say that my 20TB FC will be 40TB after compression or only store the data compressed so that I can store more? Also, how can I see the current FC is compressed or not? >> >> >>Thanks, >>Thomas >>On Friday, May 9, 2014 6:53 PM, Craig Dickman <dmarc-noreply_at_freelists.org> wrote: >> >>As Carol said, you're correct. I should have been more specific. >> >> >> >>________________________________ >> From: George Leonard - Business Connexion <George.Leonard_at_bcx.co.za> >>To: "dmarc-noreply_at_freelists.org" <dmarc-noreply@freelists.org> >>Cc: ORACLE- L <oracle-l_at_freelists.org>; Roy <royxavier@yahoo.com> >>Sent: Friday, May 9, 2014 4:29 AM >>Subject: Re: Exadata Cacheflash Compression >> >> >> >>Hi Craig >> >> >>You say with X4... is this not a way of behaviour thats associated more with a SW release number, compared to a HW model/range? >> >> >> >> >>Yours Sincerely >> >> >>________________________________________ >>George Leonard >>Oracle Engineered System Specialist >> >> >>Mobile: +27.82 655 2466 >>eMail: george.leonard_at_bcx.co.za >>Web: http://www.bcx.com >> >> >> >>On 08 May 2014, at 5:26 PM, Craig Dickman <dmarc-noreply_at_freelists.org> wrote: >> >>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@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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