WLM, DB2, and enclaves - the inside story - IBM

WLM, DB2, and enclaves: 

the inside story 

Session # 2515 

Share Feb. 1999 

Gail Whistance 

whist@us.ibm.com 

WLM Design/Development Team 

Poughkeepsie, NY 12601 

Copyright IBM Corporation 1999 

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WLM, DB2, and enclaves - the inside story 

Copyrights and Trademarks 

(c) Copyright IBM Corporation 1999. 

Database 2, MVS/ESA, OS/390, and RACF are trademarks of the International 

Business Machines Corporation. 

IBM and DB2 are registered trademarks of the International Business Machines 

Corporation. 

SHARE Session 2515 (c) copyright IBM Corporation 1999 Feb. 1999 

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Agenda 

What is an enclave anyway? 

What problems are being solved? 

DB2 V4 - distributed DB2 requests (DDF) 

DB2 V5 - sysplex query parallelism 

DB2 V5 - stored SQL procedures 

Other workloads using enclaves 


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What is an enclave? 

Represents a "business unit of work" 

Is managed separately from the address space 

Can include multiple SRBs/TCBs 

SRBs are preemptible type 

Can span multiple address spaces 

Can have many enclaves in a single address space 

Exists in both goal and compatability mode 

assigned to service class or PGN 

managed separately from address space 


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DDF 


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Management of DDF Work 

Problem: 

Heavy DDF loads can 

prevent entry of new 

requests 

No way to manage DDF 

transactions 

individually...everything runs 

with the ssnmDIST address 

space's controls 

Solution: 

Make DDF transactions 

visible to SRM as enclaves 

Individually, classified, 

managed, and reported 

Subject to period switch 

Work is run under SRBs 

that are dispatched like 

tasks rather than like local 

SRBs 


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Previous DDF Implementation 

ssnmDIST 

ssnmDBM1 

Local SRB 

PC to run SQL 

Data/rc returned 

Network 

Task 

SMF 30, 72 

CPU time 


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Managing DDF Work in DB2 V4R1 

ssnmDIST 

ssnmDBM1 

Network Task 

Enclave 1 

SRB 

PC to run query 

Rows returned 

Enclave 2 

SRB 

Enc 2 

Enc1 

DDF SMF 30 CPU 

Enclave 

SMF 72 

CPU time 

DDF SMF 72 CPU time 


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Enclave Accounting 

Each enclave represents an individual SRM transaction 

Transaction counts and resource usage are recorded in the 

SMF 72 record for the enclave's service class and report class 

No SMF 30 records for enclaves themselves. Transaction 

counts and resource usage are recorded in the SMF 30 of the 

owning address space. 

CPU time consumed by enclaves is recorded in the SMF 89 

records of home address space for usage-based pricing. 

SRBs scheduled to an enclave are preemptible, like tasks. 


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Each enclave represents an individual SRM transaction. An enclave 

transaction is assigned to a service class or pgn, and its resource usage 

and execution delays are tracked separately from the address spaces 

where it runs. 

Enclave transaction counts and resource usage are recorded in the SMF 

72 record for the enclave's service class/pgn and report class/rpgn for 

installation accounting and chargeback. In addition, the resource using and 

delay data for enclaves is reported with the service/report class of the 

enclave, not with the service/report class of the address space where it 

runs. 

Enclave transaction counts and resource usage are recorded in the SMF 

30 records for the address space which created the enclave (the owner 

address space). There are no separate SMF 30 records for enclaves. 

CPU time consumed by enclaves is recorded in the SMF 89 records of 

each home address space in which an enclave SRB runs (the participating 

address space(s)) for usage-based pricing but is not included in the SMF 

30 or 72 records for those address space(s). 

Because SRBs scheduled to an enclave are preemptible, like tasks, their 

CPU time is counted as CPU service, not SRB service. 

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Classifying DDF Transactions 

All enclaves, including DDF transactions, are classified using 

the active MVS WLM policy in both compatibility and goal 

modes 

In compat mode the ICS can be used to map a service class to 

a performance group, and likewise for reporting 

Can classify using new attributes: plan, package, etc. 

Defaults if you do not classify in WLM policy: 

Goal mode: enclaves default to the SYSOTHER service 

class which has a discretionary goal! 

Compat mode: any enclaves run in the pgn/rpgn of the 

owning address space (DDF) as they did before 


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You do not have to be in a multisystem sysplex or running in WLM goal mode to 

exploit transaction management via DDF enclaves. DB2 V4 DDF always creates 

enclaves for its work when running on MVS 5.2.0 or above, or on OS/390. 

To classify DDF enclaves you must do all of the following: 

1. Format a MVS Workload Manager couple dataset. 

2. Use the WLM administrative application to create a service definition with 

classification rules for subsystem type DDF, and at least one service class. 

The goal of the service class(es) is irrelevant if you are running in WLM 

compatibility mode, that is using parmlib members IEAIPSxx and IEAICSxx 

to manage work. 

3. Install the service definition on the WLM couple dataset and activate a policy. 

4. If you are running in WLM compatibility mode, you must also update the 

IEAICSxx parmlib member by adding rules for subsystem DDF: 

SUBSYS=DDF, /* a pgn here is ignored if coded */ 

SRVCLASS=x,PGN=y,RPGN=z /* "x" is the service class assigned in 

the WLM classification rules */ 

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Managing DDF Work (Enclaves) 

Transactions are subject to period switch 

Goal mode: 

All goal types allowed 

Compat mode: 

Performance groups and report performance groups can be 

assigned using SUBSYS=DDF 

Limit of one rpgn 

Time slicing is ignored 

Domain is ignored 


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What is a Transaction? 

DRDA request 1 DRDA request 2 

Queue time 

Execution time 

Idle 

Queue time 

Execution time 

hreads = 

nactive 

Active 

Inactive 

Active 

Inactive 

Enclave transaction 

managed by SRM 

Enclave transaction 

managed by SRM 

hreads = 

Active 

Database thread is active from creation until termination 

Enclave transaction managed by SRM exhibits conversational behavior 


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What Goals Should I Use? 

WLM compatibility mode 

Goal does not matter. Service class used only to associate 

an enclave with a performance group. 

WLM goal mode 

THREADS=INACTIVE and RELEASE(COMMIT) 

DDF creates one enclave per active interval 

Response times do not include think time 

Response time goals and multiple periods can be used 

THREADS=ACTIVE or RELEASE(DEALLOCATE) 

DDF creates one enclave for the life of the thread 

Enclave response time includes think time 

Response time goals should not be used 

Multiple periods should not be used 


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Definition of CPU Service has Changed 

Philosophical refinement 

Compatible with the existing definition 

CPU time/service are no longer synonymous with "task 

time/service" 

CPU time/service now includes contributions from all 

preemptible dispatchable units: tasks, client SRBs, enclave 

SRBs 

SRB time/service is unchanged - it includes contributions from 

all non-preemptible dispatchable units: local and global SRBs 


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SMF Type 30 Record Changes 

No changes are required to existing accounting packages 

Existing CPU time and service fields include enclave SRB 

contributions 

For all enclaves created by the address space, new fields 

contain: 

enclave active time 

transaction count 

CPU time and service 

I/O times and I/O count 


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SMF Type 72 Record Changes 

No changes are required to existing accounting packages 

Existing CPU service fields include enclave SRB contributions 

Other existing fields include data from enclave transactions: 

Active time 

Response time 

Transaction count 

Number of "address spaces" sampled 

I/O times and I/O count 

Resources consumed by the DDF transactions are no longer 

reported in the DDF address space's SMF 72 record unless the 

enclaves are in the same service class/pgn as DDF 


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Enclave System Effects (DDF) 

(Lots) more transactions. Each DDF transaction used to be 

part of the DDF address space SRM transaction, now SRM 

sees each DDF transaction. 

Increased active time since more transactions exist 

Large decrease in DDF SRB time/service in SMF 30 record 

Corresponding increase in CPU time/service in the service 

classes/performance groups where enclaves are running 

MSO and I/O service is unchanged 

DDF logons are not held up by existing DDF work 


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Sysplex Query Parallelism 


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Sysplex Query Parallelism 

Supports data mining applications 

DB2 query can be split across parallel sysplex 

Requires DB2 V5.1 and DB2 data sharing 

Classification of originator doesn't change 

Classification of participants is under 'DB2' rules 

Classification attributes inherited from originator 

Accounting is done on the system where enclave runs 

Each remote piece starts in 1st period 


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DB2 Stored Procedures 


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What is a stored procedure? 

MVS 

client 

EXEC SQL 

CALL PROCX 

DB2 

schedule PROCX 

perform SQL 

perform SQL 

perform SQL 

return data 


Address Space 

EXEC SQL 

SELECT . . . 

EXEC SQL 

UPDATE . . . 

EXEC SQL 

INSERT . . . 

proc end 


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Why Use Stored Procedures? 

Reduce network send/receive operations for distributed 

applications 

Reduce elapsed time 

Encapsulate business logic and database design at the server 

Protect sensitive data 

Eliminate need for end user DB2 table authority 

Simplify management of application programs 

Perform online change without impacting clients 

Reduce cost of porting client code to other platforms 


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Limitations in DB2 V4R1 

All stored procedures execute in 1 address space 

Multiple procedures can execute concurrently 

(NUMTCB parameter in ssnSPAS JCL procedure) 

Number of tasks limited by storage constraints below 16M 

A programming error in one stored procedure might affect 

other procedures running at the same time 

All stored procedure requests are treated equally 

Queued FIFO 

Executed at dispatch priority of ssnSPAS address space 

From an MVS perspective, CPU time is charged to the 

ssnSPAS address space 

RACF userid of ssnSPAS address space is used for access to 

non-SQL resources 


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Stored Procedures in DB2 V5R1 and OS/390 R3 

WLM work Queue 

Application XYZ 

SQL work 

DB2 Subsystem 


Process "CALL" 

Enclave 

Application ABC 


Enclaves 

Address space management in goal mode 


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Code the stored procedure 

Preparation 

Bind the stored procedure to a package 

Code the application to call the stored procedure 

Grant authorization to execute the stored procedure 

to the application 


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Definition 

Create a JCL procedure for the stored procedure address 

space 

Define an application environment to WLM 

Authorize the stored procedure address space to connect to 

DB2 and WLM 

Define the stored procedures to DB2 


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Accounting 

Where is service for stored procedures accumulated? 

For DDF work 

CPU service is included in the SMF 30 record for the DDF 

address space, and the SMF 72 record for the enclave's 

service class period 

For all other work 

CPU and MSO service is included in the SMF 30 record of 

the client's address space, and the SMF 72 record for the 

client's service class period 

IOC and SRB service is included in the SMF 30 and 72 records 

for the stored procedure address space 


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Stored Procedures Summary 

Use stored procedures to improve the response time of 

distributed applications, and to encapsulate data management 

logic at the server 

Use WLM to 

manage the number of stored procedure address spaces to 

meet clients' goals 

run stored procedures with controls appropriate to clients' 

goals 

Use application environments to group related stored 

procedures 


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Complex transactions and enclaves 

VTAM 

or 

TCP/IP 

DB2 (DDF) 

DB2 (MSTR) 

SRB 

SRB 

* SINGLE REPORTED TRANSACTION 

* MULTIPLE DISPATCHABLE UNITS 

Enclave 

* MIXTURE OF TCB AND SRB 

* NO ADDRESS SPACE BOUNDARIES 

* SINGLE WLM GOAL AND MANAGEMENT ACTIONS 

WLM 


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Putting the Pieces Together 

DB2 gives you: 

V4R1: DDF exploitation of enclaves 

V5R1: Sysplex query parallelism 

V5R1: Stored SQL procedures 

MVS gives you: 

MVS 5.2: Refined definition of CPU time and service 

MVS 5.2: SRM transactions: enclaves 

OS/390 R3: TCBs in enclaves, server management 

Together these can improve the response time and systems 

management of DB2 work. 


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Who else uses enclaves? 


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Other workloads using enclaves include: 

Websphere http Server for OS/390 (IWEB) 

LAN Server for MVS (LSFM) 

Component Broker (CB) 

MQ/Series Workflow 

. . . (expect more) 

In goal mode, make sure you classify them... 

default is SYSOTHER. 

Keep SYSOTHER empty so it can be used 

as warning signal. 


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Hot tips 

Don't forget to classify. 

Keep work out of SYSOTHER service class. 

Know how your DDF transactions are defined. 

Check out WLM home page. 

If new to goal mode, start with Cheryl Watson's Quick 

Start Policy. 

Select initial goals from peak periods in compat 

mode. 

When adding new workloads, classify them. 


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Summary 

Enclaves enable full WLM control 

DB2 is a premier user of enclaves 

Expect other workloads to use enclaves in future 

Often used in conjunction with sysplex routing and 

server space management 

Enclaves strengthen S/390's industry-leading 

workload management 


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IBM Education Courses 

H3995 Parallel Sysplex Implementation (45 minutes on WLM) 

H4013 Workload Manager Workshop 

H3986 Migration 

H3988 Measurement and Tuning - compatibility to goal mode migration 

H3989 Migration 

ES540 OS/390 Workload-Based Performance Management (new!) 

(check http://www.training.ibm.com around 4/1/99) 

MVS Planning: Workload Management (GC28-1761) -- a must have. 

MVS Programming: Workload Management Services (GC28-1773) 

Chapter on Enclaves including a chart showing how accounting is done. 

Chapter on Queueing Manager Services shows DB2 model 

DB2 for OS/390 V5 Administration Guide (SC26-8957) -- DB2 use of enclaves 

WLM home page: http://www.ibm.com/s390/wlm 

For latest papers, presentations, and frequently asked questions 


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WLM, DB2, and enclaves - the inside story - IBM

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