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Re:[IDMSVENDOR-L] DASD Upgrades

  • 1.  Re:[IDMSVENDOR-L] DASD Upgrades

    Posted 02-04-2009 09:37 AM
    Our service provider announced plans to upgrade DASD hardware from mod-3

    (3,339 cyl) to mod-L (32,760 cyl). =20



    Currently we have many multi-file areas with some exceeding 50 files.

    The general approach is to keep allocation down to roughly 12,500 tracks

    (quarter volume) for each file. I was told this allowed for flexibility

    when having to perform these migrations (and there's probably other

    reasons) but I'm not convinced this is a good way to manage our database

    files.



    Would it be practical to allocate DB files to the volume's maximum size

    when necessary? Any general rules to follow when allocating large

    areas?



    TIA,

    Brian Hirman

    R16.0 SP4 z/OS 1.9



    =20
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    Normal

    Normal
    Re: DASD Upgrades
    "I have created myself a rule, no dataset is bigger than 200 cylinders=
    .=20
    If I need more, I split the area into many 200 cylinder files. Like=
    =20
    this, I have all the flexibility to move my database files, they are =
    all=20
    200 cylinders. well most of them. So if I have access to a new pack,=
    =20
    then I can start moving those 200 cylinder files as I wish. They are=
    =20
    interchangeable.

    Voil=E0,
    Daniel Bureau
    Ajilon Consulting
    Montr=E9al

    Hall, Dan (GE Comm Fin) a =E9crit :
    Brian,
    One drawback to allocating a DB file to the maximum number of track=
    s is,
    what happens if an area unexpectedly fills up? You have painted you=
    rself
    into a corner. You cannot perform a quick EXPAND PAGE to correct th=
    e
    problem. The larger page size would automatically mean you are goin=
    g to
    use more tracks than are available on a single volume. These would =
    force
    you to perform an Unload/Reload to correct the problem, this means =
    a
    much larger outage time.

    We try to allocate the DB files 1/2 the maximum number of tracks, j=
    ust
    for this reason.

    Another issue is, how often do you have completely empty production
    volumes sitting around when you need to allocate files? It is usual=
    ly a
    lot easier (at least for me) to find a fraction of a volume than it=
    is
    to find a completely empty volume.


    Dan Hall=20
    Database Administrator=20
    GE Capital Solutions=20

    T 513 217 5060=20
    E dan.hall@ge.com=20
    www.ge.com/capitalsolutions/=20

    Middletown, OH 45042=20
    General Electric Capital Corporation=20

    GE imagination at work=20