Creating VSAM files

The z/OS NFS supports three types of VSAM files: key-sequenced (KSDS), entry-sequenced (ESDS), and relative record (RRDS). However, keyed access and relative-number access to the files are not supported. Maximum file size supported for any VSAM file type is less than 4GB. VSAM files should not be defined as EXTENDED ADDRESSABILITY even though the file size may be less than 4GB. See z/OS DFSMS Using Data Sets for additional information on MVS file size limits.

If you plan to update a VSAM data set (for example, with the vi editor or with the cp copy command), the data set must have been defined with the reuse option. Trying to write back a VSAM data set that was not defined as reusable results in an "I/O error", "failure to open", or similar error message. If you create a VSAM file using the NFS, the reuse option is used by the server.

For more information on VSAM files, see z/OS DFSMS Using Data Sets.

In the following example for creating a VSAM KSDS file, the attributes indicate that:

Spanned records are allowed
Organization is key-sequenced
Keys are 8 bytes long and start in position 0 of each record
Average record size is 1024
Maximum record size is 4096
Space is allocated for 50 records with a secondary allocation of 10
Cross-region and cross-system share options are provided
The file is to be created on a volume named D80CAT

$ cp ksds.old "ksds.new2,spanned,dsorg(indexed),keys(8,0),
   recordsize(1K,4K),space(50,10),shareoptions(1,3),
   vol(D80CAT)"

In the following example for creating a VSAM ESDS file, the attributes indicate that:

Spanned records are allowed
Organization is entry-sequenced
Average record size is 1024
Maximum record size is 4096
Space is allocated for 50 records with a secondary allocation of 10
Cross-region and cross-system share options are provided
The file is to be created on a volume named D80CAT

$ cp esds.old "esds.new3,spanned,dsorg(nonindexed),
   recordsize(1K,4K),space(50,10),shareoptions(1,3),
   vol(D80CAT)"

In the following example for creating a VSAM RRDS file, the attributes indicate that:

Spanned records are not allowed
Organization is relative record, numbered in ascending order
Average record size is 1024
Maximum record size is 1024
Space is allocated for 50 records with a secondary allocation of 10
Cross-region and cross-system share options are provided
The file is to be created on a volume named D80CAT

$ cp rrds.old "rrds.new4,nonspanned,dsorg(numbered),
   recordsize(1K,1K),space(50,10),shareoptions(1,3),
   vol(D80CAT)"