measuring the effects of system recovery boost

Measuring the effects of

System Recovery Boost

Fabio Massimo Ottaviani

EPV Technologies

[email protected]

Agenda

Overview

Relevant SMF fields

Effects on CPU and zIIP measurements

Support in EPV for z/OS V16

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Overview

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Overview

… Built into IBM z15, System Recovery Boost is an innovative solution that diminishes the impact of downtime, planned or unplanned, so you can restore service and recover workloads substantially faster than on previous IBM Z generations with zero increase in IBM software MSU consumption or cost

With System Recovery Boost, you can use your already-entitled Central Processors and zIIPs to unleash additional processing capacity on an LPAR-by-LPAR basis, providing a fixed-duration performance boost to reduce the length and mitigate the impact of downtime …

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from IBM System Recovery Boost – Frequently asked questions

Overview

In this overview will discuss:

▪ Boost class: Shutdown, IPL, Recovery process

▪ Boost type: Speed, zIIP

▪ System parameters

▪ System commands

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Overview – Shutdown and IPL 6

from IBM System Recovery Boost – Frequently asked questions

Overview – Shutdown

You need to run the IEASDBS (IEA Shut Down Boost Start)

procedure at shutdown to trigger System Recovery Boost

The length of the boost interval is 30 minutes (or until the

system stops)

If your system automation takes more than 30 minutes to

shutdown the system you should run IEASDBS when the CPU

needs are the highest to get the most benefits

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Overview - IPL

No special action is required; System Recovery Boost is

activated automatically

The length of the boost interval is 60 minutes

Part of the boost interval can be exploited to process backlog

faster

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Overview – Recovery process

Recovery process allows to reduce the disruption caused by the following sysplex recovery activities and to expedite the return to steady-state operations:

▪ Sysplex partitioning

▪ CF structure recovery

▪ CF datasharing member recovery

▪ HyperSwap

Individual recovery process boost lasts up to five minutes each, and you can use up to thirty minutes worth of these boosts in a consecutive 24-hour period (per LPAR)

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Overview – Speed Boost

When the z15 is configured as a subcapacity model, LPARs that are running in a boost period can access the Speed Boost and run at full speed

The following subcapacity models are available:

▪ IBM z15 T01 subcapacity models are 4xx, 5xx, and 6xx, where xx is 1 – 34; model 7xx is the full capacity model

▪ IBM z15 T02 subcapacity models are A0x - Y0x, where x is 1 – 6; model Z0x is the full capacity model.

Speed Boost applies to general purpose processors (GCP) only; zIIPs already run at full speed

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Overview – zIIP boost

While zIIP Boost is active, z/OS will make zIIP eligible, work which is normally not zIIP eligible

In case an LPAR has some zIIPs that are defined as reserved, and some number of those can be backed by physical zIIPs, those reserved zIIPs will be brought online during the boost period

zIIP Boost works whether you are running in PROCVIEW CORE or PROCVIEW CPU mode, or whether or not your zIIPs are running in SMT mode

If you have no zIIPs defined to an LPAR, you will see no benefit from zIIP Boost

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Overview - Parameters

System Recovery Boost can be controlled via the BOOST

parameter in the IEASYSxx parmlib member:

▪ SYSTEM is the default setting; all boost types will be

exploited

▪ ZIIP will only allow for zIIP Boost

▪ SPEED will only allow for GCP Speed Boost

▪ NONE will disable all types of boosting

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Overview - Commands

D IPLINFO,BOOST RESPONSE=PROD

IEE255I SYSTEM PARAMETER 'BOOST': SYSTEM

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Overview - Commands

/D IPLINFO,BOOST,STATE

RESPONSE=TEST

IEE257I Boost State

Boost class: N/A

zIIP boost: inactive

Speed boost: inactive

D IPLINFO,BOOST,STATE

RESPONSE=PROD

IEE257I Boost State

Boost class: IPL

zIIP boost: active with 5 transient zIIP cores

Speed boost: active

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Relevant SMF fields

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Relevant SMF fields

The following information is provided in SMF records:

▪ Boost class; it is the reason of the boost; it can be IPL,

Shutdown or Recovery process

▪ Boost type; it can be zIIP, Speed or both

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Relevant SMF fields

SMF30_BoostInfo; bit meaning when set:

▪ Bit 0, zIIP boost

▪ Bit 1, Speed boost

▪ Bits 5-7 (*):

✓001, IPL

✓010, Shutdown

✓011, Recovery process

(*) The boost class value is valid only when one or more boost type is active

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Relevant SMF fields

SMF70_BoostInfo; bit meaning when set:



SMF70FLA; 2-bytes existing flag; bit meaning when set:



▪ Bits 13-15 (*):

✓ 001, IPL

✓ 010, Shutdown

✓ 011, Recovery process


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Relevant SMF fields

SMF72FLA; 2-bytes existing flag; bit meaning when set:



▪ Bits 13-15 (*):

✓001, IPL

✓010, Shutdown

✓011, Recovery process


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Relevant SMF fields

SMF79FLA has the same layout as SMF72FLA

SMF89_BoostInfo and SMF89T2_BoostInfo have the same

layout as SMF30_BoostInfo

SMF99_BoostInfo has the same layout as SMF30_BoostInfo

with a couple of bits more

More information, including boost start and end time, is

provided in the new subtype 40 of SMF 90

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Effect on CPU and zIIP

measurements

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Effects on CPU and zIIP measurements - Case 1

Machine is an IBM 8561-716

Analyzed system IPLed at 21:57 on 16th August 2021

System is sharing 5 CPUs and 8 zIIPs

BOOST parameter not specified so SYSTEM default applies

Only zIIP Boost expected

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At system level:

CPU consumptions look normal

zIIP consumptions very high in the IPL hour


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But service class total CPU consumptions look very high after IPL; for 1 hour


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The badnews is thatservice classes seems to use more MSU than the system


Boost

end

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The good news is thatthe MSU 4HRA is notimpacted

CPU unboostedtime isprovided in SMF 70



Machine is an IBM 8562-T05

Analyzed system IPLed at 20:18 on 6th July 2021

System is sharing 2 CPUs and 2 zIIPs

BOOST parameter not specified so SYSTEM default applies

Both Speed and zIIP Boost expected

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At system level:

CPU consumptions look low at beginning and grows later

zIIP consumptions high in some intervals of the IPL hour



Also in this case, workload consumptions exceeded system

consumptions

It indicates the system got zIIP boost benefits

We tried to evaluate the Speed Boost benefits

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We analyzed the hourly profile of the CPU sec / MIPS ratio of WLM

We expected to see a reduction caused by the speed boost (CEC MIPS are the same because not in SMF while less CPU time should be needed )

As you can see the ratio remained stable in the IPL hour

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Effects on CPU and zIIP measurements

During the zIIP boost, at workload level it’s impossible to distinguish between zIIP eligible and not eligible work overflowing to CPU

During the Speed boost, SMF records that contain capacity information, such as 30, 70-1, 72-3, and 89, will reflect the unboosted capacity of the image, not the effective boosted capacity

BOTTOM LINE

Don’t use boost intervals for capacity management

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Added BOOST indication (o) in the WORKLOADS views header


Added BOOST controls in changes

Every modification of boost status will be logged

Both boost type and boost class

Enabled by default

You can disable it in CHANGES

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SYSTEM CHANGES SERIAL YES CEC OF SYSTEM

SYSTEM CHANGES REALCPU YES CPUS IN LPAR

SYSTEM CHANGES LCPUDE YES DEDICATED CPUS IN LPAR

SYSTEM CHANGES LCPUSH YES SHARED CPUS IN LPAR

SYSTEM CHANGES LIIPDE YES DEDICATED IIPS IN LPAR

SYSTEM CHANGES LIIPSH YES SHARED IIPS IN LPAR

SYSTEM CHANGES CENTSTORE YES SYSTEM CENTRAL STORAGE

SYSTEM CHANGES MVSLVL YES SYSTEM OS LEVEL

SYSTEM CHANGES RMFVER YES SYSTEM RMF LEVEL

SYSTEM CHANGES EPV_SU YES HARDWARE SERVICE UNITS

SYSTEM CHANGES SMF70HDM YES HIPERDISPATCH ACTIVE

SYSTEM CHANGES ZIPHONOR YES IIP HONOR PRIORITY

SYSTEM CHANGES R723NFFS YES IIP NORMALIZATION

SYSTEM CHANGES SMF70PML YES BLK WKL THRESHOLD

SYSTEM CHANGES SMF70PMT YES BLK WKL CPU %

SYSTEM CHANGES SMF70MTID YES PROCVIEW CORE

SYSTEM CHANGES MTIIP YES MT IIP THREADS

SYSTEM CHANGES BOOSTINFO YES BOOST TYPE

SYSTEM CHANGES BOOSTCLASS YES BOOST REASON


Example of boost changes at IPL

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Questions ?

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measuring the effects of system recovery boost

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