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  • 1.  DS8900F and extent pool creations... small or big extent?

    Posted Tue May 07, 2024 03:31 AM

    I need to set up a new DS8950F to be virtualized behind an SVC cluster, which extent size should I use, small or big? I have a lot of conflicting advice about that. Any thoughts?

    Thanks in advance.



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    Sergio Pardos
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  • 2.  RE: DS8900F and extent pool creations... small or big extent?

    Posted Thu May 09, 2024 05:40 PM

    Hello Sergio,  When I virtualized my DS8886's a few years ago, I also asked around and the consensus from various support groups was to match the DS8 extent size with the existing SVC pool extent sizes.  In my case that was 1GB.



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    IBM-SAN Admin
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    Original Message


  • 3.  RE: DS8900F and extent pool creations... small or big extent?

    Posted Fri May 10, 2024 01:27 AM

    Thanks for your answer. I also have heard about matching the extent sizes of both platforms, but on the other side, I am also reading about how the small extents are more space efficient and also more effective easy tier wise...

    Best regards.



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    Sergio Pardos
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    Original Message


  • 4.  RE: DS8900F and extent pool creations... small or big extent?

    Posted Fri May 10, 2024 12:14 PM
    Edited by Luis Lopez Fri May 10, 2024 12:14 PM

    Hola Sergio!

    Did you take a look at the SVC and Flashsystems Best Pratices Redbook?

    https://www.redbooks.ibm.com/redbooks/pdfs/sg248508.pdf

    There are specifics about it:

    1. For pool extent size planning, consider the following recommendations:

      •   For standard pools, usually 1 GB is suitable.

      •   For Data Reduction Pools use 4 GB (see 3.7, "Data Reduction Pools Best Practices" on page 126 for further considerations on extent size on DRP).

      •   With Easy Tier enabled hybrid pools, consider smaller extent sizes to better utilize the higher tier resources and therefore provide better performance.

      •   Keep the same extent size for all pools if possible. The extent-based migration function is not supported between pools with different extent sizes. However, you can use volume mirroring to create copies between storage pools with different extent sizes.



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    Luis Lopez
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    Original Message


  • 5.  RE: DS8900F and extent pool creations... small or big extent?

    Posted Sat May 11, 2024 08:05 AM

    Hola Luis

    Such bp, if I understand it well, pertains to the extent size in the SVC, my question is about the extent size in the DS8k.

    Thanks anyway for your input.



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    Sergio Pardos
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    Original Message