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  • 1.  Storage for snaps from an Exadata dSource

    Posted 04-29-2021 04:52:00 PM
    We're in the process of moving our production DB which is used for our dSource from x86 to Exadata.  We're aware that data from Exadata will not be compressed and that we will need to add storage to Delphix that is equal to the size of the Exadata DB.  My question is, assuming snapshots of this dSource will also not be compressed, how can we estimate the extra storage that will need to be added to handle those snapshots?  Is there a way to estimate this based on the snapshots of the current dSource?

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    David Linde
    GPS Non-Prod Environment Support
    Optum
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  • 2.  RE: Storage for snaps from an Exadata dSource

    Posted 04-30-2021 11:07:00 AM
    David,

    Delphix storage needs are not impacted by compression done on the storage tier of the database, whether this is Exadata or a different storage tier that performs compression/dedupe.

    The snapsync processes uses RMAN, which will provide the database blocks uncompressed (or compressed via it's own mechanism) and then Delphix will apply it's own compression method.

    Example:  a 10 TB Oracle database source leverages 10 TB of traditional storage, but today only needs 3 TB of Delphix storage to hold the dSource.  If you migrate this database to Exadata and enable HCC features, it might take only 9 TB of Exadata storage.  But your Delphix storage needs are the same:  3 TB.

    One Gotcha is Transparent Data Encryption (TDE).  If you also enable TDE as part of your migration, and you weren't using it before, this can really change your Delphix storage compression.  Encrypted blocks in general do not compress well.  If you encrypted your entire 10 TB of data, you might now need 10 TB of Delphix storage.  Strictly speaking, this isn't because of Exadata, but we see that sometimes TDE is enabled as part of that migration.

    This example of course is strictly concerning the dSource size, not your VDB storage needs.  You will obviously need Delphix storage to handle the blocks which are unique for your VDBs.



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    Ranzo Taylor
    Technical Services Director
    Delphix
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    Original Message


  • 3.  RE: Storage for snaps from an Exadata dSource

    Posted 04-30-2021 12:26:00 PM
    Hi Ranzo,

    We will be using TDE on the source DB and we have already planned on adding storage to our Delphix engine.  The target DBs will not be using Exadata or TDE.  The new DB is 24 and we are adding storage to cover this.  I'm assuming that snapshots of the dSource will be using more storage, but I have no idea how to calculate how much more.  We currently have snapshots ranging is size from 44 GB to 1 TB, depending on how old the snapshot is.  So, in order the plan for storage needs I need some way to determine if a 1TB snapshot would turn into 1.2 TB or 10 TB..

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    David Linde
    GPS Non-Prod Environment Support
    Optum
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    Original Message


  • 4.  RE: Storage for snaps from an Exadata dSource
    Best Answer

    Posted 05-03-2021 07:02:00 PM
    Delphix Professional Services can assist you David.  I've reached out to someone on my team, and they will be working with you to try to predict your needs as accurately as possible.

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    Ranzo Taylor
    Technical Services Director
    Delphix
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    Original Message


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