Storing and Managing Data in Today’s z/OS

Environment

Michael E. Friske

Storage Challenges

Compounded growth Cost reduction pressure Changing regulatory and business

requirements Higher availability requirements Data life cycle management

Hardware Solutions That Can Help Address These

Challenges Storage Tiering

– IBM DS8870 with EasyTier– EMC VMAX with FAST– HDS VSP with HDS Dynamic Tiering

Virtual Tape– IBM DS7700– EMC DLm

– Oracle VSM– CA-Vtape

(software/hardware)

Traditional Storage Hierarchy

High Performance

Low Cost

Cache or SSD

Enterprise Disk

ML1 Disk

ML2 Tape

Data Life Cycle

Active data– Stored on primary disk

Less active data– Migrate to ML1 disk– Uses MIP’s– Must be recalled to use

Inactive data– Migrate to ML2 tape– Uses MIP’s– Must recall to use

Primary Disk

ML1Disk

ML2Tape

SMS MGMTCLAS

Number of days on primary disk Number of days on ML1 volumes When to expire

Management criteria– Number of days since the create date– Number of days since the last reference

date

Disk Options Flash Drives (100GB, 200GB, 400GB,

1.6TB, and 3.2TB) Solid State Drives (400GB) SAS Drives

– 10,000 RPM (300GB, 600GB, 900GB, and 1.2TB

– 15,000 RPM (146GB and 300GB) Nearline SAS Drives

– 7,200 RPM (1TB, 2TB, 3TB, and 4TB)

Determining What Data Went on Which Drives

Disk subsystems with a mix of different types of disk drives– Analyze RMF and/or SMF reports– Map SMS storage groups to specific disk

drives– Monitor for changes in access patterns

A homogenous disk subsystem that works for all types of data

Hardware Based Tier Management

IBM DS8870 EMC VMAX HDS VSP

Easy Tier Fully Automated Storage Tiering (FAST)

HDS Dynamic Tiering

First Generation Tiering

The Disk subsystem monitored the I/O activity for each extent

Extents were dynamically relocated to different tiers based on internal algorithms

Shortcomings of First Generation Tiering

Data is moved at the extent level, not on a data set boundary

Data sets move around due to reorgs, defrags, copying, etc.

Patterns of access change based on the time of day or the day of the week

Data is placed on a storage tier based on access, not SLA’s

Addressing the Shortcomings

Hints from the host– z/OS 2.1 Class Transitions– Hitachi Tiered Storage Manager

MGMTCLAS - Expiration

MGMTCLAS - Migration

MGMTCLAS – Class Transition

MGMTCLAS – Transition Technique

Easy Tier with Class Transition

Enterprise$

Nearline½ $

Class transition after 120 days

Migrate after 366 days

Recall

Transition Copy Technique

FRP - FR PREFERRED FRR - FR REQUIRED STD - STANDARD PMP - FC PRESMIRPREF PMR - FC PRESMIRREQ

Serialization Error Exit

DB2 - Invoke DB2 to close and unallocate the object. If this is successful, the object is serialized and moved and DB2 is invoked to reopen the object.

CICS - Invoke CICS to take the object offline. If this is successful, the object is serialized and moved and CICS is invoked to reopen the object.

ZFS - Invoke zFS to unmount the data set. If this is successful, the data set is serialized and moved and zFS is invoked to remount the data set.

EXIT - Enables users / ISVs to provide an exit that will be invoked before and after transitioning an allocated data set. The data set is only transitioned if serialization is obtained after the first invocation of the exit.

NONE

Transition Invokes the ACS Routines

Once DFSMShsm determines that a data set has met the Class Transition criteria specified by the Management Class, it invokes the ACS routines to determine what the transition should be– ACS Routines are invoked with new ACS environment

(&ACSENVIR) of SPMGCLTR, for 'space management class transition'

– The following routines are invoked (in this order)» Storage Class» Management Class» Storage Group

– Any or all can be transitioned If the classes and storage group returned match the existing

classes and storage group, then no transition occurs

STORCLAS Routine

IF &ACSENVIR = 'SPMGCLTR' THEN SELECT (&STORCLAS)

WHEN (‘FLASH') SET &STORCLAS = 'EASYTIER'OTHERWISE SET &STORCLAS = &STORCLAS

ENDELSE ...IBM

MGMTCLAS Routine

IF &ACSENVIR = 'SPMGCLTR' THEN SELECT (&MGMTCLAS) WHEN ('NOML2') SET &MGMTCLAS = 'ML2OK' WHEN ('DB2NEW') SET &MGMTCLAS = 'DB2AGED' OTHERWISE SET &MGMTCLAS = &MGMTCLAS ENDELSE...IBM

STORGRP Routine

IF &ACSENVIR = 'SPMGCLTR' THEN SELECT (&STORCLAS) WHEN (‘FLASH') SET &STORGRP = 'TIER0' WHEN ('EASYTIER') SET &STORGRP = 'TIER1' OTHERWISE SET &STORGRP = &STORGRP ENDELSE ...IBM

Example – New Data Set Initial access

– Random reads & writes with periods of high access

STORGRP = TIER0– Flash– Enterprise

MGMTCLAS– No migration– Transition after 60

days

Flash

Nearline

Enterprise

TIER1

TIER0

Example – Access Drops Off

Access after 3 months– Accessed less– No write activity

STORGRP = TIER1– Enterprise– Nearline

MGMTCLAS– Migrate after 30

days of inactivity– Expire after 7 years

Flash

Nearline

Enterprise

TIER1

TIER0

Transition after 60 days

Example - Inactive

Flash

Nearline

Enterprise

TIER1

TIER0 Virtual Tape

Recall

Migrate

Cost Savings

Reduce CPU costs by eliminating ML1– No need to compress or decompress data– Eliminate recalls from ML1

Reduce CPU costs with Class Transition– May be able to use FlashCopy– May be able to wait longer before migrating to

ML2 Reduce the purchase price for new disk

subsystems

Virtual Tape Subsystems

IBM TS7720 EMC DLm Oracle VSM

Cost Reduction with Virtual Tape

Reduces floor space requirements Reduces the need for tape handlers Replicate tape data to remote site for

disaster recovery Batch cycle runs faster Tapeless tape subsystems

– Eliminate the need to tape handlers– No need to buy physical tape media

zEnterprise Data Compression

zEDC Express is an IO adapter that does high performance industry standard compression

Used by z/OS Operating System components, IBM Middleware, and ISV product

Required z/OS 2.1 and EC12 or BC12

SMS Compression with zEDC

Can be used in place of generic or tailored compression for QSAM and BSAM data sets

CPU savings for existing users of SMS compression

Disk savings for users who are not currently using SMS compression

Other Features That Can Reduce HSM CPU

Consuption Use RLS to access the HSM CDS’s Replace Interval Migration with On-Demand

Migration Take advantage of Multiple Address Space HSM

(MASH) support Implement the Common Recall Queue Implement Fast Subsequent Migration Avoid reorganizing the HSM CDS’s too frequently HOLD LOG if log data is not required

RLS for HSM CDS’s

Reduces CPU overhead for HSM due to less calls to GRS, less buffer invalidation, and less I/O to disk

Reduces elapse times for long running tasks like Primary Space Management, Secondary Space Management, EXPIREBV, Recycle, and Audit

HSM On-Demand Migration

Does not check every volume each hour to see if the volume is over the high threshold

Eliminates the spike in CPU usage for HSM at the top of each hour

Will only process a volume once after it goes over the high threshold

HSM MASH

Can be used to run HSM backup and space management functions at a lower priority (different WLM Velocity Goals)

Can be used to spread tasks out to more address spaces and to reduce SYSZTIOT contention

HSM Common Recall Queue

Allows multiple hosts to process recalls Can be used to limit tape processing on certain CPU’s Helps with workload balancing Multiple recalls for different data sets on the same

tape from different CPU’s can be processed on a single CPU

Allows higher priority requests across the sysplex to get process first over lower priority requests

Keeps recall requests if HSM is shut down or goes down unexpectantly

Fast Subsequent Migration

Saves CPU costs associated with re-migrating data sets that were recalled but not updated

Reduces the need to run RECYCLE

HSM CDS Reduction

Turn on CA Reclaim for the HSM CDS’s Do not reorganize the HSM CDS’s just

because they have CI and CA splits Only reorganize the HSM CDS’s to

reclaim space

Other Cost Avoidance Measures

Clean up the errors HSM finds each night

Analyze MGMTCLAS definitions periodically, and adjust them if necessary

Check for data sets in the wrong MGMTCLAS

Data That Can Be Used for Analysis

HSM Logs HSM FSR records DCOLLECT data

Questions ?