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Diffrence between Dcelaring CYL or TRK in Space parameter ?

 
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pinchoo335

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PostPosted: Fri Jun 06, 2008 2:20 pm    Post subject: Diffrence between Dcelaring CYL or TRK in Space parameter ?
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What difference does it make.. Performace and access wise to allocate Space to a file in Cylinder or Track ?
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expat

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PostPosted: Fri Jun 06, 2008 2:39 pm    Post subject:
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With modern DASD subsystems, there will be no discernible performance differences.
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pinchoo335

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PostPosted: Fri Jun 06, 2008 3:00 pm    Post subject: Reply to: Diffrence between Dcelaring CYL or TRK in Space pa
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I am told to change all the Current JOBS in production,
I have to change CYL to TRK,
If space parameter is CYL (1,2). I have to change it to TRK(15,30)
I am not very sure why they asked me to do it, But i was just told that it is for better performance and access
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expat

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PostPosted: Fri Jun 06, 2008 3:08 pm    Post subject:
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Quote:
I am not very sure why they asked me to do it, But i was just told that it is for better performance and access

In the old days with classic DASD it was always better to allocate in CYL for anything over 75 tracks. But with modern DASD subsystems there will be NO performance gains by doing this.

My guess is that someone has discovered that they could possibly save a couple of hundred CYLS in allocated but unused space.

With the cost of DASD per Mb against the cost of your time, this to me seems a waste of resource.

But hey, Good luck icon_biggrin.gif
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gcicchet

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PostPosted: Fri Jun 06, 2008 3:11 pm    Post subject:
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Hi,
the other advantage with using tracks is for small files you dont waste as much space.

eg. if a file uses 1 trk then 1 cyl would waste 14 trks.


Gerry
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pinchoo335

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PostPosted: Fri Jun 06, 2008 3:34 pm    Post subject:
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But i am already Multiplying the space by 15 while allocating the space.
So it's 1 CYL or 15 TRK's i don't think it will make much difference ?
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expat

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PostPosted: Fri Jun 06, 2008 3:39 pm    Post subject:
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It will with the RLSE parameter
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Aaru

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PostPosted: Fri Jun 06, 2008 3:42 pm    Post subject: Reply to: Diffrence between Dcelaring CYL or TRK in Space pa
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Quote:
eg. if a file uses 1 trk then 1 cyl would waste 14 trks.


You can use the RLSE parameter to release the unused space.
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gcicchet

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PostPosted: Fri Jun 06, 2008 3:51 pm    Post subject:
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Hi,
when release is used on a cyl, the smallest unit is still 1 cyl, hence a 1 trk file using 1 cyl will waste 14 trks.


Gerry
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