Question & Answer
Question
What is the limit for data set extents? Is this limit the same in Version 6 and Version 7 of DB2® UDB for OS/390®?
Answer
A VSAM data set can be expanded to 123 extents per volume. If this data set is a multi-volume VSAM data set, the VSAM component can be extended to a maximum of 255 extents combined over all volumes.
VSAM uses the following algorithm to enforce these limits: "allow allocations until an allocation might exceed the limits." If currently 118 extents exist on a volume, another allocation can be made. This allocation can be up to 5 extents, which gives the full 123 extents. If 119 extents exist, another allocation exceeds the 123 extent limit (119+5=124) and rather than trying and sometimes failing, VSAM just fails the request.
This limit is the same in Version 6 and Version 7.
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Document Information
Modified date:
16 June 2018
UID
swg21159598