STOGROUPs and SMS [DB2 9 for z/OS]

With today’s posting we return to our examination of the new features of DB2 9 for z/OS. With V9, DB2 storage groups can be better integrated with SMS storage classes.

Prior to DB2 9, you could only spcify SMS storage classes, data classes, and management classes when using explicit IDCAMS defines. You could use those SMS specifications with your SMS ACS routings, but ACS routines filter on data set names, so those routines could become large and unwieldy if you defined multiple different combinations for different data sets.

The improvement in DB2 9 modifies the CREATE and ALTER STOGROUP statements to utilize SMS classes. This can greatly improve ease-of-use by minimizing the manual effort involved in managing DB2 data sets using DFSMS.

There are three new keywords in the CREATE STOGROUP syntax. You can specify just one, two or even all three of them on one CREATE STOGROUP statement:

• DATACLAS - influences characteristics such as the data set control block (DCB), striping, extended format usage, extended addressability usage and so on.
  
• MGMTCLAS – defines data set frequency of volume backups, migration requirement and related tasks.
  
• STORCLAS - define guaranteed spaced and other requirements.

DB2 will not check to verify that the data class, management class, or storage class specified actually exist. In that regard, the parameters are designed to work the same way that the VCAT and VOLUMES parameters have always worked. When the STOGROUP is used to allocate a data set, the specified classes are passed to DFSMS, which does the actual work.

The intent of this posting is not to act as an SMS tutorial. If you wish to investigate the details of SMS in more depth, consult the IBM manual titled -- z/OS DFSMS Implementing System-Managed Storage, SC26-7407.

Additionally, these same parameters have been added to the ALTER STOGROUP statement. When you alter SMS class names of a DB2 STOGROUP, this does not affect the existing data sets. However, if you run the REORG, RECOVER, or LOAD REPLACE utility, DB2 deletes the associated data set and redefines it using the new description of the storage group.

Finally, to accommodate the metadata for these new parameters, three new columns have been added to the SYSIBM.SYSSTOGROUP DB2 catalog table: DATACLAS, MGMTCLAS, and STORCLAS.

On Database Skills and DBA Salaries

Just a quick post today to point you over to my Data Management Today blog. I use this blog to talk about data management issues that are not specific to DB2, whereas this blog focuses almost exclusively on DB2 (and mainframe) topics.

But two recent posts at my other blog may be of interest to readers of my DB2 Portal blog. They deal with the topics of employability and pay -- two topics that are near and dear to the heart of IT and database professionals.

Here are links to those posts:

• DBA Salary Update - a look at a couple of recent salary surveys
  
• Database Skills Are In Demand - a look at a recent study on IT skills

If you find these posts interesting, subscribe to my Data Management Today blog (via RSS) and/or check in regularly.

Mainframe Career Still a Good Idea!

Just a quick post today to point you over to an article that ran in eWeek Magazine titled Big Iron Remains Career Option. Those of us who have worked with mainframes for decades know that mainframes still run the bulk of the mission-critical, high transaction workload for the biggest companies. And we know that you can make a good career out of mainframe development, administration, and management.

But it is good news that others are starting to hear this message.

Indexing the DB2 Catalog [DB2 9 for z/OS]

First of all, I want to apologize for the lack of new posts here the last couple of weeks. I've been busy traveling and preparing for the holidays -- as have most of you I guess, at least the holiday preparation part! Anyway, this will likely be my last post this year and it will be a short one at that. But be sure to check back again in the new year (2008) as I will begin posting a bit more regularly again (hopefully).

In today's post I want to tout a small but helpful improvement in DB2 9 for z/OS that makes it easier to build all of the indexes you want on your DB2 Catalog tables. As you know, even though the DB2 Catalog ships with a set of pre-defined indexes from IBM, you can add your own for improving the performance of your catalog queries. Some DB2 tools vendors even ship recommendations of indexes for you to build to make their solutions work more efficiently.

Well, prior to V9 the limit for user-defined defined indexes on the DB2 Catalog was 100. Over time, some shops have bumped up against this limit and were unable to define any additional indexes.

The good news is that DB2 V9 ups the limit to 500 user-defined catalog indexes.

That's all for today... and I wish all of my readers a very happy holiday season!

UPDATE SCHEMA and CATMAINT [DB2 9 for z/OS]

Welcome back to my blog as I continue our examination of the new features of DB2 9 for z/OS. Today we will look at the new UPDATE SCHEMA capability of the CATMAINT utility.

Have you ever wanted to make a global change to a schema, owner, creator, or VCAT name for your DB2 objects? Well, you can do that with CATMAINT in DB2 9 for z/OS using new UPDATE SCHEMA options.

There are three (3) new options added to CATMAINT, namely:

• SCHEMA: Owner, creator and schema names can be changed using this option.
• VCAT: Indexes, table spaces and storage groups can be altered to use a different ICF or VCATNAME using this option.
• OWNER: Ownership of objects can be changed to a role using this option.

To use any of these options you must be in DB2 9 NFM and have Install SYSADM authority.

How does it work? Well, let’s take a look at a few examples, starting with the SCHEMA option. To rename the owner, creator, and schema of database objects, plan, and packages, we will run CATMAINT specifying the SCHEMA SWITCH option. This process updates every owner, creator or schema name in the catalog and directory that matches the specified schema_name value. Importantly, all GRANTs that were made by or received by the original owner are changed to the new owner. Ownership of objects is not changed if the owner is a role.

So if we want to change OLDNAME to NEWNAME we can code the following CATMAINT job:

CATMAINT UPDATE
SCHEMA SWITCH(OLDNAME, NEWNAME)

You can change multiple names by repeating the SWITCH keyword, but you are not allowed to code the same name more than once.

Be aware though, when the schema name of an object is changed, any plans or packages that are dependent on the object are invalidated. If you do not REBIND those plans and packages an automatic REBIND will occur the next time you execute any of those programs.

Here is another example, this time for the VCAT option. To change the VCAT name that is used by storage groups or by index spaces and table spaces, we can run CATMAINT specifying the VCAT SWITCH option. This option is similar to using the ALTER TABLESPACE USING VCAT statement for changing the VCAT name. You need to move the data for the affected indexes or table spaces to the data set on the new catalog in a separate step.

So if we want to change OLDVCAT to NEWVCAT we can code the following CATMAINT job:

CATMAINT UPDATE
VCAT SWITCH(OLDVCAT, NEWVCAT)

You can change multiple VCAT names by repeating the SWITCH keyword, but you cannot specify the same name more than once. There are several restrictions to this option that you should research in the IBM manuals before attempting to switch VCAT names.

The final option is the OWNER option. It is used for changing the ownership of objects from a user to a role. Roles are new in DB2 9 and are associated with a TRUSTED CONTEXT. This will be the subject of a future blog posting here on the DB2portal blog – so keep an eye out for that one soon.

For example, if we want to switch ownership of objects for OWNER1, OWNER2 and OWNER3 to a role, we can run CATMAINT as follows:

CATMAINT UPDATE
OWNER FROM(OWNER1, OWNER2, OWNER3) TO ROLE

You must be running under a trusted context with a role to run this utility. The current role will become the owner. Privileges held on the object will be transferred from the original owner to the role.

A final caveat: be sure to create backups of your DB2 Catalog and DB2 Directory before running this CATMAINT to switch SCHEMA, VCAT, or OWNER.