IBM Mainframe Forum

by **D9988** » Fri Mar 06, 2009 11:05 pm

Hello. Is it possible to determine the approximate size of a dataset in megabytes based off the dataset information? I do not know if you can estimate this based off used cylinders alone, or if there is a formula that takes into account the record length along with the blocksize/used cylinders? Can anyone describe how to determine the file size based upon this data set information please?

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General Data Current Allocation
Management class . . : I2WBRA1Y Allocated cylinders : 100
Storage class . . . : NORMAL Allocated extents . : 2
Volume serial . . . : PT9C57
Device type . . . . : 3390
Data class . . . . . : **None** Current Utilization
Organization . . . : PS Used cylinders . . : 63
Record format . . . : FBA Used extents . . . : 2
Record length . . . : 133
Block size . . . . : 931
1st extent cylinders: 50
Secondary cylinders : 50
Data set name type : SMS Compressible : NO

by **dick scherrer** » Sat Mar 07, 2009 12:23 am

Hello,

One easy way for a small file like this is to copy the file to a DD DUMMY output which will give you the record count (without actually creating a new file). Then multiply the recount times the lrecl and you get file size in bytes. Dividing total bytes by 1024 will give how many k/m bytes.

The other way to calculate the size is to determine how many blocks will fit onto a track and work from there. Look at the info at this link:
http://publibz.boulder.ibm.com/cgi-bin/ ... 1001/B.1.2
"Without keys" is for normal sequential files.

by **D9988** » Thu Mar 12, 2009 2:28 am

Thanks Dick, very helpful information

IBM Mainframe Forum

How to determine approx size of dataset in Megabytes

How to determine approx size of dataset in Megabytes

Re: How to determine approx size of dataset in Megabytes

Re: How to determine approx size of dataset in Megabytes