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VSAM file Storage Calculation


IBM Mainframe Forums -> JCL & VSAM
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inforajesh

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Joined: 09 Dec 2020
Posts: 15
Location: India

PostPosted: Fri Mar 19, 2021 12:32 pm
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Hello,

My requirement was to find space consumption of particular VSAM file and extrapolate for full year.(To communicate SMS team)
Performed LISTCAT and found the actual used values. However can someone help me how to extrapolate for one year (In Cylinder values)

LISTCAT Details

STATISTICS
REC-TOTAL-------------15 SPLITS-CI--------------0 EXCPS-----------------22
REC-DELETED------------0 SPLITS-CA--------------0 EXTENTS----------------1
REC-INSERTED-----------0 FREESPACE-%CI----------0 SYSTEM-TIMESTAMP:
REC-UPDATED------------0 FREESPACE-%CA----------0 X'D96E1C21533BCE25'
REC-RETRIEVED---------10 FREESPC-----------688128

ALLOCATION
SPACE-TYPE------CYLINDER HI-A-RBA----------720896 EXTENT-NUMBER----------1
SPACE-PRI--------------1 HI-U-RBA-----------32768 EXTENT-TYPE--------X'00'

IDCAMS SYSTEM SERVICES
SPACE-SEC--------------1
VOLUME
VOLSER------------WORK12 PHYREC-SIZE--------16384 HI-A-RBA----------720896 EXTENT-NUMBER----------1
DEVTYPE------X'3010200F' PHYRECS/TRK------------3 HI-U-RBA-----------32768 EXTENT-TYPE--------X'00'
VOLFLAG------------PRIME TRACKS/CA-------------15
EXTENTS:
LOW-CCHH-----X'02B50000' LOW-RBA----------------0
HIGH-CCHH----X'02B5000E' HIGH-RBA----------720895
EXTENTS:
LOW-CCHH-----X'02B50000' LOW-RBA----------------0 TRACKS----------------15
HIGH-CCHH----X'02B5000E' HIGH-RBA----------720895


Actual used :
HI-U-RBA : 32768
HI-A-RBA : 720896

(HURBA / HARBA) = Ratio used

32768 / 720896 = 0.0454545454545455

Total allocated cylinder * Ratio used = Actual used
1 * 0.045 = 0.045



Based on this result, can someone help me to extrapolate the storage (cylinder) for full year ?

Thanks
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Joerg.Findeisen

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Joined: 15 Aug 2015
Posts: 563
Location: Bamberg, Germany

PostPosted: Fri Mar 19, 2021 1:10 pm
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You can use a Crystal Ball to find the amount of data being added to the VSAM cluster for a year. What a stupid requirement.
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Willy Jensen

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Joined: 01 Sep 2015
Posts: 477
Location: Denmark

PostPosted: Fri Mar 19, 2021 1:28 pm
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Are an equal number of records added each month? No records updated or deleted? Then take the current size divide with the number of months the cluster have been in existence and multiply by 12. Again assuming an equal number of records added per month. The result will most likely be way off the mark. Whatever approach you take, be sure to monitor the size of the cluster regularly and make sure that there is space enough on the disk to allow for expansion.
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Joerg.Findeisen

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Joined: 15 Aug 2015
Posts: 563
Location: Bamberg, Germany

PostPosted: Fri Mar 19, 2021 1:33 pm
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When you make the VSAM SMS EA/ECR you can have 7257 Extents (59 x 123). So based on current allocation, that would be the time when Aliens take over world domination.
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