What's new in EPV for Db2 and EPV Graph for Db2 V15

What's new in EPV for Db2 and

EPV Graph for Db2 V15

Massimo Orlando

EPV Technologies

[email protected]

XIX EPV User Group

Agenda

EPV for Db2 enhancements

EPV Graph for Db2 enhancements

New version plan

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Introduction

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Introduction

In this presentation we will focus on some of the most relevant

enhancements introduced in EPV for Db2 and EPV Graph for

Db2 V15

Many other enhancements have been introduced but they will

not be discussed here

This version provides full support of z15 and Db2 12

It also fully supports the new EPV UI

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Continuous delivery information

Fast Traverse Block

Accelerator exploiters

Plan Unlock/Commit Ratio

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Continuous Delivery

In Db2 V12, IBM adopted the continuous delivery model

The idea is to deliver enhancements in the service stream without

waiting for a massive new release

Continuous delivery should solve two main customer issues:

▪ Customers saw deployment of new releases as disruptive,

making them reluctant to move to a new release, which inhibited

their ability to take advantage of new features

▪ Many customers wanted new functions delivered much faster (not

every 3 years as it happened with Db2 V11 and before)

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With continuous delivery it’s very important being able to check

the levels of Db2 code, catalog and functions used

This information is not provided in any SMF records

It can be easily collected by running a JCL step which executes

the DISPLAY GROUP command, on each Db2 subsystems

This JCL is provided in EPV for Db2 and it should be already

used in previous versions to collect Db2 parameters and

statistics

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Continuous Delivery

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Continuous Delivery


Continuous Delivery


Continuous Delivery

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Fast Traverse Block

Many Db2 applications rely heavily on one or more indexes on each

table in order to locate specific data rows efficiently

Db2 indexes use a classic “b-tree” structure with a root page,

usually one or more levels of non-leaf pages and leaf pages pointing

to the data pages

The more levels of index, the higher the cost in terms of the number

of get pages, consequent CPU cycles required and elapsed time

If the index levels don’t reside in a buffer pool, there will be an

additional penalty due to the required I/O operations

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Fast Traverse Block

To perform more efficient random index lookups Db2 12

introduces the index Fast Traverse Block (FTB) function

With FTB, Db2 will cache root and non-leaf page information in

the FTB storage pool but only for UNIQUE indexes with a key

size of 64 bytes or less

Db2 will automatically and dynamically decide which indexes to

cache based on current workload access patterns

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A new Db2 storage pool has been created in V12 to host the FTBs; its size is determined by the INDEX_MEMORY_CONTROL parameter

Possible values are:

▪ AUTO; Db2 will size the FTB storage pool to the maximum between 20% of the total allocated buffer pool size and 500MB; it’s the default

▪ DISABLE; Db2 will disable the FTB functionality

▪ A value in the 500-200.000 MB range; Db2 will size the FTB storage pool based on that value

When in data sharing it’s recommended that all members use the same setting

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Fast Traverse Block

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Fast Traverse Block 15

FTB Usage

▪ Indexes, is the number of indexes with FTB blocks

▪ Size, is the total FTB size in bytes

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Fast Traverse Block 16

FTB Usage

▪ Index Levels, is the number of index levels with FTB blocks

▪ Size, is the total FTB size in bytes

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EPV for Db2 already provided information about accelerator

utilization …

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… and accelerator activity in previous versions

More details are available by clicking the server id link

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In EPV for Db2 V15 we introduced views which allows to

analyze the TOP accelerator exploiters:

▪ by CPU time

▪ by elapsed time

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Lock avoidance is a combination of techniques used by Db2 to

retrieve data without requiring holding a shared lock on behalf of the

application process, if some conditions are met

In this case, Db2 will take a page latch (and page p-lock in data

sharing) to ensure physical consistency of the page instead of a lock

It only applies to low level locks (page and row)

The application has no direct control over it

But applications not committing frequently enough may disrupt it

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An Unlock/Commit Ratio (UCR) greater than 5 will indicates

that lock avoidance is not exploited well

EPV for Db2 already provided this info at the subsystem level

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LOCK ACTIVITY 7 8 9 10 11 12 13 14 15 16 17 18 19LOCK REQ/SEC 17.955 16.285 15.191 37.449 40.204 31.742 25.629 28.229 29.254 18.243 13.554 32.555 25.774

LOCK CHGD/SEC 851 2.132 864 590 525 518 474 569 497 373 355 718 727

LOCK QRY/SEC 0 0 0 0 0 0 0 0 0 0 0 0 0

UNLOCK/SEC 5.880 4.434 4.637 21.646 11.656 8.042 6.171 6.660 8.060 4.303 3.346 5.918 5.868

COMMIT/SEC 698 934 453 491 408 440 346 377 406 358 428 639 970

UNLOCK/COMMIT 8 5 10 44 29 18 18 18 20 12 8 9 6

LOCK SUSP/SEC 9 20 13 10 7 8 7 9 8 7 8 8 11

IRLM LATCH SUSP/SEC 305 318 108 219 201 201 121 192 224 114 197 3.437 1.283

OTHER SUSP/SEC 4 2 2 4 2 3 3 2 2 2 3 5 3

IRLM LATCH CONTENTION 1 1 1 0 0 0 0 1 1 0 1 9 4

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Plan unlock/commit ratio

In EPV for Db2 V15 we calculate and publish the UCR for the

TOP transactions (CICS, IMS), authids (DDF, SAF) and plans

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Latch analysis

EDM pools efficiency

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Latch analysis

In EPV Graph for Db2 V15 we added graphs showing the daily

profile and the daily trends of the latch rate at data sharing

group subsystem and latch class level

All the latch classes (more than 30) are reported

We also provide monthly trends for long term analysis

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Latch analysis – Sharing group26

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Latch analysis - Subsystem27

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Latch analysis – Latch class28

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In EPV Graph for Db2 V15 we added graphs showing the daily

profile and the daily trends of the hit ratio of:

▪ DBD pool; it should be close to 100%

▪ SKELETON pool; Cursor Tables for plans and Package Tables

for packages; they should also be close to 100%

▪ Global Dynamic Statement Cache; it should be more than 95%

Also in this case, we provide monthly trends for long term

analysis

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Daily trends of

the skeleton

cursor tables

hit ratio in the

different time

shifts

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Daily trends of the skeleton package tables hit ratio

Only prime shift has been selected in the graph

We also zoomed the graph (see Y axis)

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New version plan

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New version plan

EPV for Db2 and EPV Graph for Db2 will continue to evolve

V16 is planned by mid 2022

It will include all V16 new features and enhancements (see

EPV for z/OS V16 preview)

It will support z16 (?) machines (expected in Spring 2022)

It will continue to support new Db2 function levels and versions

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Questions ?

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Documents

What's new in EPV for Db2 and EPV Graph for Db2 V15