Allocation of Instant Snapshots

Instant Snapshots require the use of dynamic allocation and output copies to DASD.

Instant Snapshot output data sets cannot be GDG data sets. However, output data set names can be constructed using symbolic variables (Using-GDGs-and-symbolic-variables-in-data-set-names).

Related topic

Operational-considerations

Important

For Instant Snapshot copies, DSNAME on the OUTPUT or COPY command is the VSAM cluster name. The maximum length of DSNAME for Instant Snapshots is 39 characters. The same is true for COPYDSN, RECOVERYDSN, BIGDSN, and BIGRECDSN on the COPY command. For Instant Snapshots on EMC hardware, there is also a limit of 5 nodes for DSNAME. Note that FULLDSN and FULLRECDSN are acceptable only with FULL AUTO or CHANGELIMIT. Also note that if you use the VOLUMES option on the OUTPUT command, there must be enough space on the first specified volume to allocate the primary space required for the output data set.

The target allocation information must meet the requirements of the associated hardware in order to use the copy facilities. The source data set must also meet hardware requirements to utilize hardware copy features. For details about supported hardware devices and their requirements for source and target devices, see the Installation System.

Important

Instant Snapshots may not work correctly for some storage vendors when the Db2 parameter MGEXTSZ is set and the primary and secondary extents are less than a cylinder.

Certain catalog and directory spaces are allocated and copied by the IBM Db2 COPY utility.

 

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