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6 Replies Latest reply: May 8, 2012 10:56 AM by gsalem RSS

Dbfs on exadata - compression recommendation?

Daryl E. Explorer
Currently Being Moderated
The best practices/setup doc 1054431.1 doesn't mention anything about compression for the tablespace holding the dbfs data. Understanding of course a performance penalty, has anything been written about a desirable configuration settings for this?
  • 1. Re: Dbfs on exadata - compression recommendation?
    603349 Explorer
    Currently Being Moderated
    I assume you are talking about the advance options?

    sqlplus <username>/<password>@<database>
    @$ORACLE_HOME/rdbms/admin/dbfs_create_filesystem_advanced.sql
    <tablespace name> <file system name>
    <compress-high | compress-medium | compress-low | nocompress>
    <deduplicate | nodeduplicate>
    <encrypt | noencrypt>
    <partition | non-partition>


    My suggestion is to explore and test with different options to satisfy your specific requirements.

    --
    Regards,
    Greg Rahn | blog | twitter | linkedin
  • 2. Re: Dbfs on exadata - compression recommendation?
    Daryl E. Explorer
    Currently Being Moderated
    Right - advanced .. with Exadata you paid for it. Surprising the setup docs and best practices make no mention of it.

    I would think this would be a good place to make use of compression - as long as the performance penalty isnt too great.


    Oh wait (no dbfs expert here) .. this appears to be different compression then that set at the tablespace level. Is that why its not set at the tablespace level perhaps?
  • 3. Re: Dbfs on exadata - compression recommendation?
    603349 Explorer
    Currently Being Moderated
    Technically DBFS is available for non-Exadata as well, so it's included in the Oracle license itself, nothing related to Exadata.

    The compression that is used by DBFS is not OLTP or Direct Path compression, which you can set at the tablespace level, it is Secure File compression. Looking at the docs,
    http://docs.oracle.com/cd/E11882_01/appdev.112/e18294/adlob_smart.htm
    it appears that Secure File compression and deduplication are part of the Oracle Advanced Compression Option, but I'm not 100% sure how that works with DBFS. Let me see what I can find there...

    But using compression anywhere is about trade offs, it makes sense and adds benefits in some cases and in others the tradeoffs are not beneficial. Depends on your specific case.

    --
    Regards,
    Greg Rahn | blog | twitter | linkedin
  • 4. Re: Dbfs on exadata - compression recommendation?
    Daryl E. Explorer
    Currently Being Moderated
    Thanks - I was looking specifically at the Exadata flavour of DBFS - ie compression like archive high/low query high/low. Like to make the best use of the cell disks that we have. (qtr/half and full)
  • 5. Re: Dbfs on exadata - compression recommendation?
    603349 Explorer
    Currently Being Moderated
    Daryl E. wrote:
    Thanks - I was looking specifically at the Exadata flavour of DBFS - ie compression like archive high/low query high/low.
    That's my point - there isn't any specific Exadata flavour -- it's all the same Exadata or not.

    I did get confirmation that since DBFS compression really is SecureFiles compression and deduplication, it does require the Advanced Compression Option.

    --
    Regards,
    Greg Rahn | blog | twitter | linkedin
  • 6. Re: Dbfs on exadata - compression recommendation?
    gsalem Explorer
    Currently Being Moderated
    A point to consider here is what are you, or will be, using dbfs for. If it is to store files before loading them into the database, then advantages of using compression or deduplication... will depend on these files. If they are gzipped, or for example some kind of images, ... then securefile compression will not help. But if the files are not compressed, it may help a lot. But, as Greg said, it is more function of what you're doing with them, and the trrade offs you can make between cpu power used to comrpess/decompress, and space usage.

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