Tips for Working With Display ASP Vary Status

Practical insights on working with IASPs during and after the VARY ON process.

Practical insights on working with IASPs during and after the VARY ON process.

Ancient cave dwellers were always looking for new ways to organize their mammoth and saber-toothed tiger barbecues. What better way than with independent auxiliary storage pools (IASPs)? No more hitting each other over the head on how to arrange the data. Now they could manage each month’s mammoth orders in one IASP and the saber-toothed tiger orders in another.

IASPs became available on IBM i in release V5R2M0. They offer many advantages for customers’ production and test environments. This article assumes you’ve already decided to use IASPs and won’t elaborate on the benefits. Details of installing and configuring an IASP are available at the System i* and i5/OS* Information Center ( The Systems management Disk management publication ( contains information on how to install and configure IASPs.

This article provides practical insights on working with your IASPs during and after the VARY ON process. We’ll also address some of the limitations of IASPs and how to avoid common mistakes that can cause confusion.

The Wonderful World of IASPs

The world of IASPs can carry many benefits, and it’s important for users to understand IASP implementation. As a general rule, the same recommendation for libraries can be used for IASPs. For a library, the best practice for IBM i is to keep as many related objects as possible in the same library. This means TABLEs and VIEWs built over TABLEs should reside in the same library. Managing a single library is easier for such operations as save and restore rather than coordination of multiple libraries and their dependencies. Sometimes events dictate otherwise, but containing all related objects in the same library is a good approach. The same is true for IASPs. There are at times good reasons to cross the IASP boundary to the system ASP (*SYSBAS) for dependencies, but the idea is to keep the IASP as independent as possible.

IASP Basics

Each IASP is a DASD unit that has a name and number. CL commands and SQL statements can use the name or number to access or create objects for the IASP. An example of an IASP would be INTBDB1 with an ASP number of 033. The number 033 represents the ASP associated with the DASD units in the disk pool. An IASP can be one disk or multiple disk units. The IASP is the vehicle to dedicate storage to be used for a specific purpose. IASP numbers range from 033 to 255.

You can think of an IASP as a separate database to store objects such as TABLEs, VIEWs, data areas, etc. You can use the SQL CONNECT statement to connect to the IASP and then use an application, iSQL or another method to access the objects. An IASP even has its own System Cross Reference (XREF) files and SQL catalogs. The XREF and catalogs files contain the object entries for the IASP and the system ASP.

The concept of a library name space will raise itself throughout this article. An IASP can be thought of as a dynamic occurrence; that is, one has to vary on the IASP to make it available. If the IASP is varied off, it’s no longer available—hence, the dynamic nature of the device. With all of the IASPs on the system, you may only want to access a few. Therefore, the library name space will define the set of libraries you can reference relative to the available IASPs. The name space always includes the *SYSBAS, the job’s QTEMP library and the libraries in the set of IASPs you specify to use.

Working With the Status of Existing IASPs

To work with the current IASPs configured for your system, use the Work With Configuration Status (WRKCFGSTS) command.


For example, if you had four IASPs configured, the WRKCFGSTS command would display the type of information shown in Figure 1 on the Work with Configuration Status panel. From this display, two IASPs are available and two aren’t. Available means the IASP can be used without any functional restrictions.

Option 1 lets the user vary on the IASP such that it can be used. Option 2 will vary off the IASP such that it can’t be accessed. Varying on an IASP is similar to an IPL of the system and is done in the job that’s currently varying on the IASP. If you’re interested in knowing the current status of the VARY ON or VARY OFF within the job, the V5R4M0 Display ASP Status (DSPASPSTS) command displays the current status. If a VARY ON is under way, the DSPASPSTS command shows you the progress of the function. If the VARY ON or VARY OFF has completed, the command will display the information related to the completed VARY ON or VARY OFF.

For example, if option 1 were selected for the IASP named INTBDB1, the current job would begin to execute the code to vary on the IASP. A user from another job could enter the DSPASPSTS ASPDEV(INTBDB1) command and would see the VARY ON steps similar to an IPL.

Figure 2 is a DSPASPSTS of INTBDB1 as the IASP was being varied on. The current step is 30 out of 34 where the database cross-reference file merge is taking place. The merge does two important things. First, the object information in the *SYSBAS XREF files are merged into the IASP’s XREF files. Second, the object information in the IASP is extracted and inserted into the IASP’s XREF files.

Without specifying an LNS, you can create a library and explicitly set the IASP on the command.

Mark W. Theuer is an advisory software engineer with IBM. Mark can be reached at

Mike Venz is an advisory software engineer in the System i database organization. Mike can be reached at

Rafal P. Konik is a staff software engineer in the System i database organization. Rafal can be reached at

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