Posted: Wed May 13, 2009 1:14 am Post subject: Space Calculations - Basics.
Hi,
I know that I am asking a basic question here regarding the SPACE calculation. I must accept that I have not undestood the concept of it. I request you to please help me to make it understand
One of production dataset shows this "Data Set Information:"
Code:
Data Set Name . . . . : XXXXX.XXXXX.XXXX.XXXX.BACKUP.G0001V00
General Data Current Allocation
Management class . . : XX0001 Allocated bytes . . : 5,487,608
Storage class . . . : XX000001 Allocated extents . : 13
Volume serial . . . : VOL001
Device type . . . . : 3390
Data class . . . . . : **None** Current Utilization
Organization . . . : PS Used bytes . . . . : 5,459,610
Record format . . . : VB Used extents . . . : 13
Record length . . . : 356
Block size . . . . : 27998
1st extent bytes . : 727948
Secondary bytes . . : 356096
Data set name type : SMS Compressible : NO
Creation date . . . : 2009/05/01 Referenced date . . : 2009/05/01
Expiration date . . : ***None***
Would you please explain me how the "Current Allocation" & Current Utilization" are calculated here?
What is the significance of the below given parameters?
Code:
Data class . . . . . : **None**
Organization . . . : PS
Record format . . . : VB
Record length . . . : 356
Block size . . . . : 27998
1st extent bytes . : 727948
Secondary bytes . . : 356096
Are these parameters used to calculate "Current Allocation" & "Current Utilization"?
Lets take an example like SPACE=(CYL,(500,100),RLSE) for a file.
here the total space available for the file is Space = 500 + (100 * 15) = 2000 Cylinders.
The record count for the above said file is 2838528. Hence the used space for the file is:
Blksize = 27500, hence 110 records per track.
No:of tracks for the above said file = 2838528/110 =>25804.8 Tracks=>1721 Cylinders.
I'm able to validate the calculation with the below screen.
Code:
Data Set Information
Command ===>
Data Set Name . . . . : XXXX.XXXXX.XXXXXX.XXXXX.G0363V00
General Data Current Allocation
Management class . . : XXXX Allocated cylinders : 1,721
Storage class . . . : XXXX Allocated extents . : 9
Volume serial . . . : A1PLA5
Device type . . . . : 3390
Data class . . . . . : **None** Current Utilization
Organization . . . : PS Used cylinders . . : 1,721
Record format . . . : FB Used extents . . . : 9
Record length . . . : 500
Block size . . . . : 27500
1st extent cylinders: 500
Secondary cylinders : 100
Data set name type : SMS Compressible : NO
Creation date . . . : 2009/09/05 Referenced date . . : 2009/09/07
Expiration date . . : ***None***
I'm confused with this Space parameter: SPACE = (500,(110,11),RLSE), AVGREC=K for the same file mentioned above.
As per the IBM Manual, it states that Record length of the file is 500, the Primary quantity is of 110K( 110*1024=112640) Records and a Secondary Quantity of 11K( 11*1024=11264) Records.
I need to know how much KB will be allocated to the file. i'm confused with the calculation. The below screen is the Output dataset info with the Space parameter SPACE = (500,(110,11),RLSE).
Code:
Data Set Information
Command ===>
Data Set Name . . . . : XXXX.XXXX.XXXXXXX.XXXXXXXX.G0362V00
General Data Current Allocation
Management class . . : XXXX Allocated kilobytes : 1,385,957
Storage class . . . : XXXX Allocated extents . : 60
Volume serial . . . : A1PM70 +
Device type . . . . : 3390
Data class . . . . . : **None** Current Utilization
Organization . . . : PS Used kilobytes . . : 1,385,930
Record format . . . : FB Used extents . . . : 60
Record length . . . : 500
Block size . . . . : 27500
1st extent kilobytes: 55000
Secondary kilobytes : 5500
Data set name type : SMS Compressible : NO
Creation date . . . : 2009/09/01 Referenced date . . : 2009/09/07
Expiration date . . : ***None***
Somebody pls help me with the Allocated bytes Calculation.
Joined: 07 Feb 2003 Posts: 266 Topics: 1 Location: Edison, NJ USA
Posted: Sun Sep 27, 2009 2:53 pm Post subject:
Hi Waves,
To make things easier, try multiplying the # of recs (110K) by the len of each rec (500) = 55000K bytes. That's what the listing states - "... kilobytes: 55000" -i.e. "55,000 X 1024".
Going back to your "SPACE=(CYL,(500,100),RLSE)" question, you said:
Quote:
here the total space available for the file is Space = 500 + (100 * 15) = 2000 Cylinders.
That is the maximum space available for the file; the minimum space avail (if there is no x37 Abend generated) could be as low as 800 CYLs.
The reason for this apparent discrepancy stems from the functional difference between the definition of an "extent" and that of the 2ndary value used in the SPACE param. I'll call it an "Allocation".
While you are alloted 16 extents, each 2ndary allocation can use up to 5 entents to satisfy it. This can limit the 2ndary allocations to as few as 3 (300CYL).
This discussion applies to non-SMS allocations. Though I can't recall hearing of any SMS contradictions, you may want to check. _________________ Regards, Jack.
"A problem well stated is a problem half solved" -- Charles F. Kettering
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