Administering DBS

Introduction to DBS Administration

Once you have defined a DBS Configuration, there is no reason to change it unless your installation adds or removes tape devices. If you have included future devices in your definition (as we recommend) then the need for change is reduced even further.

Policies, on the other hand, provide flexibility. Using Policies, you can adjust DBS to adapt to the prevailing conditions. For example, Policies can reflect the difference in workload profiles during the day and overnight, or on weekends. Policies can be used to support contingency plans, such as device failures or planned maintenance outages. In short, it is likely that you will want to define several Policies. You probably do not have to change Policy definitions often, but you will want to switch Policies to meet the changing needs of the installation.

Managing the Configuration

A DBS Configuration can have only one of the following states:

• NEW: This represents the first Configuration before it is Activated.
• ACTIVE: This represents the Configuration that is in use by DBS for a particular JESplex. The ACTIVE Configuration cannot be edited.
• BACKOUT: This represents more than just the previous ACTIVE Configuration. The BACKOUT Configuration is a bridge between the previous ACTIVE Configuration and the running ACTIVE Configuration. This allows a fallback to a BACKOUT that takes into account jobs in the queue (or executing) that were processed with the NEXT Configuration but have to be adjusted to the BACKOUT.
• NEXT: This represents the future Configuration, as created by the CN command from the Configuration Management dialog.

Configuration Definition

To define a DBS Configuration, select the DBS service from the TM Automation Services menu to invoke Configuration Management. If this is your first Configuration, your only choice is to Create a NEW Configuration; otherwise, you can create the NEXT Configuration. In both cases, the command is CN.

Vendor Selection

The next step is to identify the vendors for the devices in your installation. DBS provides a structure that includes all the vendors, device types, and modes of operation that are supported. Select the appropriate vendors with the S line command.

The vendor IBM is provided as a default. If you do not have IBM devices, you can use the U line command to deselect this vendor.

Selecting a Mode and Naming a Library

After you have selected the vendors, the Drive Pool/Device Number Management figure appears, displaying a tree structure for the tape drives.

DBS needs to know the modes that you are using for your devices and, for modes that use them, the names of your libraries. The available modes are:

• IBM
  • Automated
  • Manual
  • Virtual
• StorageTek
  • Automated
  • Non-library
  • Virtual
• CA:Vtape
  • Virtual
• IBM VTFM
  • Virtual
• EMC DLm
  • Virtual

Only Pool names that begin with an asterisk (*) need to be named. The N line command invokes a pop-up window that allows you to do this, but first you must expand the tree structure so that you can choose the type of library that you want to name. A plus sign (+) indicates that a branch is collapsed, and a minus sign (-) indicates that the branch is expanded. You expand or collapse branches by placing the cursor within the Pool name and hitting ENTER. The N line command invokes a pop-up window that allows you to provide a library name.

The form for the library name varies depending on the vendor:

• For IBM, enter the 1-8 character name matching the SMS-managed library you are defining.
• For StorageTek, choose the appropriate ACS name from the list.
• For CA-Vtape and EMC DLm, you do not need to specify a name.
• For Installation Pools (described further in Using Installation Pools) enter a name of your choosing. It must be 1-8 alphanumeric or underscore characters, the first of which must be alphabetic.

Note that by implication, the named library also specifies the device mode.

Selecting Device Types

Once a library has been named, the possible devices (generic type) are shown. This could require you to expand the branch for the device type you want to select. Expand if necessary, then use the S line command to select the generic device type under which the actual drives have been grouped.

Specifying Device Numbers

The next step requires you to identify which Device Numbers belong to the selected Drive Pool.

When you select the device type, the DBS Device Numbers panel opens, allowing you to specify the range(s) of all Device Numbers available in your JESplex.

Of course, it is possible that the members in your JESplex are asymmetric, i.e. some devices are not available on all systems. To reflect this, you can use the E line command to edit the Drive Pool after you have saved the ranges available for the entire JESplex. This sequence ensures that you do not inadvertently define Device Numbers for a JESplex member that are not already defined for the whole JESplex.

Note that the way you handle asymmetric devices depends on the type of asymmetry:

• If the devices are physically unavailable to some JESplex members, use the E command to reflect this in the Configuration.
• If the devices are logically unavailable to some JESplex members, use a Policy to reflect this. For more information, see Setting Device Counts.

Normally, a device number can be assigned to one Drive Pool only. An exception occurs when you elect to use Installation Drive Pools. For more information, refer to Using Installation Pools.

Repeat the sequence of naming libraries (where required) and selecting generic device types until you describe the entire configuration for your JESplex. Upon completion, save the Configuration to finish the definition process.

Activating a Configuration

To implement a Configuration, you must use the AN command of the Configuration Management dialog to activate it:

The procedure is identical for both NEW and NEXT Configurations. The difference is that a NEW Configuration has never been activated, while a NEXT Configuration is built from a Configuration that has been activated.

When a NEXT Configuration is activated:

• The ACTIVE Configuration and Policies become the BACKOUT Configuration and Policies.
• The NEXT Configuration and Policies become the ACTIVE Configuration and Policies.
• DBS takes additional action to account for jobs that are awaiting execution:
  • Jobs that require devices that do not exist in the NEXT Configuration are detected and placed in MHS_TM HOLD for DBS.
  • Jobs that are already executing under DBS management are allowed to continue.

In both cases, DBS automatically activates the **BASE** Policy of the new ACTIVE Configuration. To activate a different Policy, follow the procedure described in Activating a Policy. Note that because you are activating a new Policy, you are also must choose between NORMAL and PASSIVE mode. For more information, see Activating a Policy.

Creating, Editing, and Replacing the NEXT Configuration

The ACTIVE Configuration cannot be edited, therefore to make changes to a Configuration you must use the CN command to create the NEXT Configuration.

The CN command results in the Edit Configuration menu. Note that if you exit from this menu without making any changes, you have not actually created the NEXT Configuration.

Because DBS cannot anticipate how your Configuration changes affect existing Policies, the newly created NEXT Configuration contains only the default **BASE** Policy. Any policies that were added to the ACTIVE Configuration, as well as any modifications that were made to the ACTIVE Configuration’s **BASE** Policy, are not copied.

Upon creating the NEXT Configuration, you are given the opportunity to modify the new **BASE** Policy if necessary. Again, we recommend that you do not change the **BASE** Policy without careful consideration. This ensures a consistent starting point to develop your specialized Policies, as well as an easily restored and predictable Policy. Instead, we recommend that you use the MN command, which allows you to add and edit Policies. For more information, see Managing Policies.

Until you activate the NEXT Configuration, you can use the EN command to edit it. If you want to start over from the beginning, you can use the RN command, which will completely replace the NEXT Configuration with a copy of the ACTIVE Configuration. Just as with the CN command, the only Policy associated with the replacement NEXT Configuration is the default **BASE** Policy.

Backing Out of a Configuration

The BACKOUT Configuration becomes available once you have activated the NEXT Configuration. The AB command restores the previous ACTIVE Configuration and Policies. If the NEXT Configuration exists, it is deleted, since it is based on the ACTIVE Configuration that is being abandoned. DBS automatically activates the **BASE** Policy of the new ACTIVE Configuration. Again, because you are activating a new Policy, you are given the choice of using NORMAL or PASSIVE mode. For more information, see Activating a Policy.

Managing Policies

Policies are associated with a Configuration and are more flexible in terms of management. For each Configuration a **BASE** Policy is created. Any number of Policies (well, almost any number) can be created and named. They are always constructed under the framework of a Configuration and are permanently associated with it.

Creating Specialized Policies

To create a specialized Policy, begin at the Configuration Management menu. Select MN to manage your Policies. This takes you to the Policy Management figure, which displays a list of your installation’s Policies. When you have just completed defining your first Configuration, the only Policy shown here is **BASE**.

The C line command creates a new Policy based on the selected Policy. You are prompted to provide a new Policy name and description. You are next given the opportunity to manage your device counts so that they reflect your specialized Policy. After copying a Policy, the Policy Edit menu allows you to modify the device counts and turn the Work Groups feature on or off. For more information, see Configuring Work Groups.

Setting Device Counts

The default **BASE** Policy assumes that:

• All device counts are equal to the number of Device Numbers that you specified in your Configuration.
• All devices are shared as described in your Configuration.

To change the device counts available to a particular JESplex member, select the Manage Device Counts entry on the Policy Edit menu and use the E line command for the Drive Pool(s) that you want to edit. In the resulting pop-up window, tab to or click on the JESplex member to be changed. Another pop-up window opens, in which you must indicate whether you want to use the default count (Y) or a modified count (N). If you select N, you are prompted to enter the new count. 

WTO Messages

For each Drive Pool, you can use the M line command to specify a WTO message that will be issued if the actual device count drops below the defined device count. This is detected during Policy activation or a DBS restart.

Activating a Policy

Policies can be activated at any time. When a new Policy is activated, DBS re-evaluates jobs that are awaiting execution and applies the new Policy to them. As a result, some jobs might now exceed the resources available to them under the new Policy. Use the Display of Jobs Exceeding Policy Resources in DBS Display Services, described in DBS Monitor and Displays to check for these jobs.

Running jobs that do not conform to the new Policy are permitted to proceed to completion.

PASSIVE Mode

When you ACTIVATE a Policy, you are asked to select Normal (default) or Passive mode. Passive mode means that DBS continues to evaluate jobs using the Configuration and Policy that was activated, but will not prevent any job or step from beginning exection. Monitors, displays, and reports still reflect activity as though DBS were operating in normal mode, providing a means of evaluation and testing.

Configuring Work Groups

If you decide that Work Groups would be of benefit, you can turn the Work Group feature ON from the Edit menu on the Action Bar.

You can also use this menu to turn the Work Group feature OFF.

If you choose to turn the Work Feature OFF, you will lose all Work Group counts that have been previously defined.

Renaming Work Groups

Turning ON the Work Groups feature activates the ability to change the default Work Group names by using the Edit menu on the Action Bar. Select Work Group Names/ Default/Options, which displays the Work Group structure. Simply tab to a Work Group and type in a new name. The name must be alphanumeric, begin with an alphabetic or national ($, #, @) character, cannot exceed eight characters, and must be unique within the Policy. Note that these are the names that are specified when selecting a Work Group using JAL or JECL.

Setting the Default Work Group

You can change the default Work Group that DBS assigns if no Work Group is assigned in JAL or through JECL by changing the number specified in the Default Work Group # field.

Turning Overbooking Off

Overbooking allows DBS to make more efficient use of the devices in a Work Group at the expense of occasional allocation contention. If you have a Work Group for which allocation contention cannot be tolerated, you can turn off the overbooking algorithm by tabbing to the Work Group and pressing Enter. This opens a pop-up window that allows you to control overbooking for that Work Group.

Setting Work Group Counts

Before beginning to set Work Group counts, we strongly recommend that you study carefully the sections Work Group Planning and The Definition Process: What Should I Have? Remember that the dialog is intended for data entry, not planning.

The dialog has been designed to eliminate confusion as much as possible, therefore a flow is enforced. For example, you cannot dedicate devices to a Work Group for a JES2 member without first dedicating drives to the Work Group at the JESplex level. Similarly, you cannot dedicate drives to a Level 2 Work Group unless drives have already been dedicated to the Work Group’s Level 1 parent.

Using Installation Pools

Installation Pools provide flexibility. All of your tape devices can be managed using the Drive Pools, but your installation might have special requirements. For example, if you have an esoteric unit name that includes different types of tape devices, you could manage them as a group by using an Installation Pool.

To define an Installation Pool, you must first name the library you will use. Installation Pools support two types of library:

• Esoteric, which you can use to map any esoteric unit names your installation might use.
• Non-esoteric, which you can use to accommodate special circumstances that cannot be handled any other way.

After you have named the library, enter the device numbers in the usual way. Note the following:

Any device number added to an Installation Pool must already exist in a Drive Pool. This is an exception to the rule that a device number must be defined in one Pool only.

For information about assigning Installation Pools using DAL, see Assigning Installation Pools.

Using JAL and JECL with DBS

DBS does not require DAL or JAL to deliver its basic benefits; however, you will probably need DAL/JAL if you want to take advantage of Work Groups.

Assigning Work Groups

Although Work Groups can be assigned using JECL, they are usually assigned in JAL with the DBS SET statement:

DBS SET WORKGROUP(PROD)The name that you specify must be one of the six Subgroups specified in the DBS Policy.

Setting DBS Priorities

In an environment without SLM, DBS Priorities are also usually assigned using the JAL statement DBS SET:

DBS SET PRIORITY(HIGH)There are three DBS Priorities:

• LOW
• MEDIUM, which is the default
• HIGH

The scope of DBS Priorities is the JESplex.

These Priorities do not affect job selection. Rather, they determine which job gets drives when contention occurs. This decision is made during step allocation.

Note that if your installation is using SLM, it will manage priorities rather than DBS.

Implied Priority

If no DBS Priority is assigned or if jobs have equal Priorities, preference is determined by the assigned Work Group. Lower numbered Work Groups, as shown in a display of the DBS Work Groups structure, are served first.

Assigning Installation Pools

Installation Drive Pools are used to define pools of tape devices that your installation has grouped at some level other than their generic device type, such as those for which your installation has created esoteric unit names. DBS manages Installation Pools in the same way that it manages normal Drive Pools. Installation Pools are assigned using the DAL statement DBS ASSIGN:

DBS ASSIGN INSTALLATION_POOL(TAPE)The DBS ASSIGN statement is the only way you can assign tape devices to Installation Drive Pools.

Unavailable Unit Handling

The way DBS handles jobs that request more devices than have been defined in the Configuration can be changed with the JAL statement DBS HOLD:

DBS HOLD UNAVAILABLE_UNITS(YES)Jobs that request more units than have been defined are normally failed with a JCL error. This statement requests that they be placed in an MHS_TM HOLD instead.

Note that such jobs can never run under the ACTIVE Configuration.

JECL for STCs

The JECL statements for DBS are intended primarily for STCs, which do not pass through Job Analysis. Although you can use these statements in ordinary batch jobs, the information provided by them should normally be provided using DAL/JAL, which always supercedes JECL.

Reserving Devices With //*+DBS RESERVE

Jobs that use tape devices without being registered with DBS are considered poachers. Because DBS has no information about poachers until they actually allocate devices, it is harder to account for their tape device usage. A job is potentially a poacher when:

• The job has one or more steps that use dynamic allocation.
• The job is a started task, which by its nature does not undergo Job Analysis.
• The job is made exempt from Job Analysis, either by its submission class or by an operator command.

You can avoid poaching and register STCs and jobs with DBS by including the //*+DBS RESERVE JECL statement:

//*+DBS RESERVE IBM->AUTOMATED->ATLDS1->3480S->3480=(1,1)This example is for an STC, and informs DBS that the STC will request one device through dynamic allocation (the first number) and one through static allocation (the second number). For batch jobs that pass through Job Analysis, the second number is ignored, since ThruPut Manager calculates the number of static allocations.

Setting Work Groups and Priorities With //*+DBS SET

You can use the JECL statement //*+DBS SET to assign Priorities and Work Groups:

Accounting for Dynamic Allocation

ThruPut Manager determines resource counts by analyzing the job’s JCL, but this method cannot account for dynamically allocated resources. In order to maintain accurate resource counts, use the DAL statement DBS RESERVE:

DBS RESERVE IBM->AUTOMATED->ATLDS1->3490->3490E(1)This statement adjusts the resource count for the IBM Automated library ATLDS1 3490E Drive Pool. Note that this statement also increases the resource counts of JAL Descriptors describing the specified unit type.

DBS Monitor and Displays

DBS provides a rich selection of monitor and display screens, as well as a report for a particular Configuration/Policy combination. There are far too many variations to include examples of each one, but the following should give you an idea of the power available from DBS Display/Monitor Services.

To invoke DBS Display/Monitor Services, first issue the TSO command under ISPF to invoke ThruPut Manager ISPF services:

TMISPFThis takes you to the Main Lobby for ThruPut Manager dialogs. Select, in order:

1. Display/Monitor Services
2. Automation File Services
3. Exit

You can now choose DBS - Drive Booking Services Display and then see options of DBS Display Services or DBS Monitor Services.

DBS Display Services

Invoking DBS Display/Monitor Services collects a snapshot of data relevant to DBS Displays. All DBS Displays show the timestamp reflecting when this snapshot was taken. To refresh the data, use the REFRESH primary command, or select the Refresh item from the View drop-down menu on the Action bar.

Using DBS Display Services, you can:

• Display the details of the ACTIVE Configuration and Policy.
• List any jobs that are requesting more devices than are available in the current Policy.

To explore the power of DBS Display Services, we recommend that you experiment with selecting JES2 members, Work Groups, and with the various line commands. The online help (F1) explains each screen and its associated line commands.

DBS Monitor Services

Invoking DBS Monitor Services begins the data collection process for the various monitor displays. In other words, it is Monitor Services that collects the data for display, not the DBS application. The collected data is updated approximately once per minute.

To use DBS Monitor Services effectively, you must allow it to run for a while, then press Enter to refresh the screen. Accumulated values will then be displayed. Using DBS Monitor Services, you can monitor drive utilization by:

DBS Configuration/Policy Report

You can generate a DBS Configuration/Policy report from the Policy Management screen by using the G line command. This report can be useful for planning and documentation purposes. Excerpts from a sample report are shown on the following pages.