StorageTek Host Software Component 6 User Manual

1st ed., 6/30/04 - 312579601

The TAPEREQ control statement is used to specify tape request attributes. TAPEREQ 
statements are read from the definition data set specified by the TREQDEF command. 
(Refer to “Tape Request Definition (TREQDEF) Command and Control Statement” on 
page 133 for details on syntax and parameters.) The TAPEREQ statement must be placed 
in the definition data set; it cannot be issued as an operator command.

To put multiple data sets on multiple volumes, a TAPEREQ statement must be coded for 
each data set name. 

As the HSC processes each allocation request, it searches the TAPEREQ statements in  the 
order that they appear in the definition data set to determine the media type, recording  
technique or model, and subpool parameters to assign to the request. One or more 
TAPEREQ statements may match the request’s input criteria. 

When there are multiple matching TAPEREQ statements containing different parameters, 
the HSC merges the parameters from the matching statements. Each parameter value is 
searched for independently, and for each, the first matching TAPEREQ statement is used. 

For this reason, StorageTek recommends that you:

• order the TAPEREQ statements from most specific to most general
• specify all applicable parameters on all TAPEREQ statements. 

Conflicting parameter assignment can result when multiple TAPEREQ statements are 
found and their parameters merged. For example, assuming the subpool REDWOOD 
contains only HELical (Redwood) cartridges, the following TAPEREQs produce 
inconsistent parameter assignment:

These statements cause the HSC to attempt to select a Standard scratch cartridge from a 
subpool that contains only helical cartridges. 

To avoid such scenarios, StorageTek recommends that all applicable parameters be coded 
on each TAPEREQ and that parameters such as SUBPool not be specified on generic 
TAPEREQ statements.  That is, MEDia and RECtech should be specified on the same 
TAPEREQ statement as SUBPool.