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pinchoo335
New User
Joined: 20 May 2008 Posts: 11 Location: Gurgaon
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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
Global Moderator
Joined: 14 Mar 2007 Posts: 8797 Location: Welsh Wales
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With modern DASD subsystems, there will be no discernible performance differences. |
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pinchoo335
New User
Joined: 20 May 2008 Posts: 11 Location: Gurgaon
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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
Global Moderator
Joined: 14 Mar 2007 Posts: 8797 Location: Welsh Wales
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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 |
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gcicchet
Senior Member
Joined: 28 Jul 2006 Posts: 1702 Location: Australia
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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
New User
Joined: 20 May 2008 Posts: 11 Location: Gurgaon
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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
Global Moderator
Joined: 14 Mar 2007 Posts: 8797 Location: Welsh Wales
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It will with the RLSE parameter |
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Aaru
Senior Member
Joined: 03 Jul 2007 Posts: 1287 Location: Chennai, India
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Quote: |
eg. if a file uses 1 trk then 1 cyl would waste 14 trks.
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You can use the RLSE parameter to release the unused space. |
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gcicchet
Senior Member
Joined: 28 Jul 2006 Posts: 1702 Location: Australia
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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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