Mainframe Storage

Mainframe Storage

Enhancing performance, reliability, and security ensuring the availability of critical business workloads

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  • 1.  How to size cache capacity?

    Posted 05/15/23 10:51 AM
    Hello Experts,
     
    Please, I'm working in a TCT implementation and I would like to ask a question related to the impact of cache (capacity) utilization.

    My customer is concerned about the capacity who HSM will consume and I would like support of how to size properly it.

    According to the Batch Magic output, looks like customer will need around 8 TBs (30 days - HSMML2 and HSMBAK), but, the Business Partner create a job to read the HSM data and the output was very different, around 150 TBs.

    Although I know the possibility of do data compression by the DS8900, I need to understand how to estimate the cache utilization.
    Is there a way to estimate the capacity? If yes, please, how to do that? Is there a compression rate that I can work?

    Thanks in advance.





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    Denis Augusto Pereira
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  • 2.  RE: How to size cache capacity?

    Posted 05/16/23 12:28 PM

    Hey Denis,

    The DFSMShsm SMF records can be used to determine the amount of data being written during DFSMShsm migration processing.  (Backup should not be included in the study because HSM Backup does not yet support TCT). FSRTYPE=3 is migration to tape and FSRTRKW (FSRF32K=0) and FSRTRKKW (FSRF32K=1) report the number of tracks written.  The TCT performance test used data with about 4:1 compression, but I would recommend a more conservative number.  Maybe 3:1?



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    Glenn Wilcock
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  • 3.  RE: How to size cache capacity?

    Posted 05/29/23 08:46 AM

    Hi Glenn,

    Sorry about my delay, busy weeks =)

    How do I ask customer to collect this report? And, after collect, it is necessary only to sum the number of all written tracks?

    Thank you.



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    Denis Augusto Pereira
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    Original Message


  • 4.  RE: How to size cache capacity?

    Posted 05/31/23 01:30 PM

    Hi Denis,

    No worries.  the client should have one or more folks who know how to create reports from SMF data.  Summing the SMF records will give the total amount of data written, which is what they are looking for.



    ------------------------------
    Glenn Wilcock
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    Original Message


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