ABCs of z/OS System Programming Volume 3 - IBM Redbooks

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SMS calculates the average preference weight of each storage group using the preference weights of the volumes that will be selected if the storage group is selected for allocation. Then, SMS selects the storage group that contains at least as many primary volumes as the stripe count and has the highest average weight. If there are no storage groups that meet these criteria, the storage group with the largest number of primary volumes is selected. If multiple storage groups have the largest number of primary volumes, the one with the highest average weight is selected. If there are still multiple storage groups that meet the selection criteria, SMS selects one at random. Storage group support Normal storage groups are preferred over overflow storage groups. The storage group sequence order as specified in the ACS storage group selection routines is supported when a multi-tiered storage group is requested in the storage class. After selecting a storage group, SMS selects volumes by their preference weight. Primary volumes are preferred over secondary volumes because they have a higher preference weight. Secondary volumes are selected when there is an insufficient number of primary volumes. If there are multiple volumes with the same preference weight, SMS selects one of the volumes at random. Data set separation Data set separation allows you to designate groups of data sets in which all SMS-managed data sets within a group are kept separate, on the physical control unit (PCU) level or the volume level, from all the other data sets in the same group. To use data set separation, you must create a data set separation profile and specify the name of the profile to the base configuration. During allocation, SMS attempts to separate the data sets listed in the profile. A data set separation profile contains at least one data set separation group. Each data set separation group specifies whether separation is at the PCU or volume level, whether it is required or preferred, and includes a list of data set names to be separated from each other during allocation. Volume preference Volume preference attributes, such as availability, accessibility, and PAV capability are supported. Fast volume selection is supported, regardless of the current specification of the FAST_VOLSEL parameter. SMS will reject the candidate volumes that do not have sufficient free space for the stripe when 100 volumes have already been rejected by DADSM for insufficient space. This is to prevent the striping allocation from overusing the system resources, because an iteration of volume reselection can consume significant overhead when there are a large number of candidate volumes. 30 ABCs of z/OS System Programming Volume 3
2.9 Large format data sets Figure 2-9 Allocating a data set with ISPF option 3.2 Large format data sets Defining large format data sets was introduced with z/OS V1R7. Large format data sets are physical sequential data sets, with generally the same characteristics as other non-extended format sequential data sets, but with the capability to grow beyond the basic format size limit of 65,535 tracks on each volume. (This is about 3,500,000,000 bytes, depending on the block size.) Large format data sets reduce the need to use multiple volumes for single data sets, especially very large ones such as spool data sets, dumps, logs, and traces. Unlike extended-format data sets, which also support greater than 65,535 tracks per volume, large format data sets are compatible with EXCP and do not need to be SMS-managed. Data sets defined as large format must be accessed using QSAM, BSAM, or EXCP. Large format data sets have a maximum of 16 extents on each volume. Each large format data set can have a maximum of 59 volumes. Therefore, a large format data set can have a maximum of 944 extents (16 times 59). A large format data set can occupy any number of tracks, without the limit of 65,535 tracks per volume. The minimum size limit for a large format data set is the same as for other sequential data sets that contain data: one track, which is about 56,000 bytes. Primary and secondary space can both exceed 65,535 tracks per volume. Large format data sets can be on SMS-managed DASD or non-SMS-managed DASD. Chapter 2. Data set basics 31
Page 1: ibm.com/redbooks Front cover ABCs o
Page 4 and 5: Note: Before using this information
Page 6 and 7: 3.10 Data sets eligible for EAV vol
Page 8 and 9: 5.5 Implementing SMS policies. . .
Page 10 and 11: 7.29 Accessing a data set with DFSM
Page 12 and 13: Trademarks IBM, the IBM logo, and i
Page 14 and 15: Paul Rogers is a Consulting IT Spec
Page 16 and 17: xiv ABCs of z/OS System Programming
Page 18 and 19: 1.1 Introduction to DFSMS IBM 3494
Page 20 and 21: Network File System The Network Fil
Page 22 and 23: Using access methods, commands, and
Page 24 and 25: Distributed data management DFSMSds
Page 26 and 27: Shelf management DFSMSrmm groups in
Page 28 and 29: Availability management DFSMShsm ba
Page 30 and 31: key functions that enable multiple
Page 32 and 33: An access method is a DFSMSdfp comp
Page 34 and 35: including the operating system itse
Page 36 and 37: 2.3 DFSMSdfp data set types Data se
Page 38 and 39: 2.4 Types of VSAM data sets Types o
Page 40 and 41: Partitioned data set (PDS) Partitio
Page 42 and 43: ► Extended-addressability, which
Page 44 and 45: method writes data on the first vol
Page 48 and 49: Restriction: The following types of
Page 50 and 51: ► REXX LISTDSI function ► CLIST
Page 52 and 53: Using CLIST OPENFILE INPUT/GETFILE
Page 54 and 55: 2.12 z/OS UNIX files Following are
Page 56 and 57: Logical records and blocks To an ap
Page 58 and 59: 2.14 Locating an existing data set
Page 60 and 61: 2.15 Uncataloged and cataloged data
Page 62 and 63: 2.17 VTOC and DSCBs VTOC DSCBs Figu
Page 64 and 65: 2.18 VTOC index structure VOLUME LA
Page 66 and 67: 2.19 Initializing a volume using IC
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Page 70 and 71: 3.1 Traditional DASD capacity 885 C
Page 72 and 73: Large volume support design conside
Page 74 and 75: DASD virtual visibility Traditional
Page 76 and 77: 3.4 WLM controlling PAVs zSeries WL
Page 78 and 79: 3.5 Parallel Access Volumes (PAVs)
Page 80 and 81: 3.6 HyperPAV feature for DS8000 ser
Page 82 and 83: For each z/OS image within the sysp
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Page 88 and 89: EAS non-eligible data sets An EAS-i
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Page 92 and 93: 3.13 Using dynamic volume expansion
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3.17 Increase capacity of volumes F
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3.19 Final capacity increase for vo
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VTOC index changes The index block
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The documentation is in Device Supp
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free space available following the
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Note: The refresh of the index occu
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Updating the VTOC following volume
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USEEAV(YES|NO) YES This means that
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Generally, for VSAM data set alloca
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attributes can reside in the extend
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Other methods for EATTR specificati
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3.30 Migration assistance tracker T
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3.31 Migration tracker commands SET
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106 ABCs of z/OS System Programming
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4.1 Overview of DFSMSdfp utilities
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4.2 IEBCOMPR utility Example 1 Exam
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4.3 IEBCOPY utility //COPY JOB ...
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4.4 IEBCOPY: Copy operation DATA.SE
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4.5 IEBCOPY: Compress operation DAT
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Copying to z/OS UNIX IEBGENER can b
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4.8 IEBGENER: Copying data to tape
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4.10 IEHLIST LISTVTOC output CONTEN
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Examples of IEHINITT In the example
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4.13 DFSMSdfp access methods DFSMSd
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physical blocks. QSAM also guarante
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The automatic class selection (ACS)
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Command Functions DEFINE PAGESPACE
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Note: These commands cannot be used
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► Capacity planning: Capacity pla
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A GDS has sequentially ordered abso
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The parameters are: NAME This speci
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4.21 Relative generation numbers A.
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4.23 PDS data set organization Adva
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4.24 Partitioned data set extended
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4.25 PDSE enhancements PDSE, two ad
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4.26 PDSE: Conversion Using DFSMSds
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4.27 Program objects in a PDSE Func
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4.28 Sequential access methods Sequ
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4.29 z/OS V1R9 QSAM - BSAM enhancem
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4.30 Virtual storage access method
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4.31 VSAM terminology Logical recor
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4.32 VSAM: Control interval (CI) LR
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4.33 VSAM data set components Clust
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4.34 VSAM key sequenced cluster (KS
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The sequence is as follows: 1. VSAM
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4.37 VSAM: Typical ESDS processing
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4.39 VSAM: Typical RRDS processing
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4.41 VSAM: Data-in-virtual (DIV) DI
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4.43 VSAM resource pool VSAM resour
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► CIs are discarded as soon as th
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SMB processing techniques If all of
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MSG=SMBBIAS When you specify MSG =
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4.47 VSAM SMB enhancement with z/OS
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4.48 VSAM enhancements Data compres
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4.50 Data set separation syntax Dat
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4.51 Data facility sort (DFSORT) Pa
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4.52 z/OS Network File System (z/OS
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4.53 DFSMS optimizer (DFSMSopt) Fig
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4.54 Data Set Services (DFSMSdss) /
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4.55 DFSMSdss: Physical and logical
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When to use logical processing Use
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When to use physical processing Use
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4.59 Hierarchical Storage Manager (
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Tasks for availability management f
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- Release of unused, over-allocated
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usually slower response time. Usual
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DATASSETSIZE(dssize) This specifies
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► Utilize OVERFLOW volumes for mi
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Before automatic secondary space ma
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For data sets larger than 58 K trac
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► Migration level 1 (ML1) volumes
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value of a user-specified RETPD or
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The second-newest version is treate
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If the version has a specified rete
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ACS routines For both automatic and
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- System-managed automated tape lib
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4.75 What DFSMSrmm can manage Remov
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You can also use the DFSMSrmm built
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z/OS V1R8 enhancements DFSMSrmm hel
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5.1 Storage management ISMF dss Fig
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5.3 Goals and benefits of system-ma
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Improved data availability manageme
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► Whether data sets are to be kep
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When the ACS routines are started a
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5.7 Assigning data to be system-man
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Even though data class is optional,
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You can use the ACCESSIBILITY attri
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If you do not explicitly assign a m
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5.12 Using storage groups DFSMShsm-
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5.13 Using aggregate backup and rec
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5.14 Automatic Class Selection (ACS
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5.15 SMS configuration An SMS confi
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5.16 SMS control data sets SMS Figu
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5.17 Implementing DFSMS Enabling th
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► Gain experience with the operat
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Specify SHAREOPTIONS(3,3) for the A
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Defining the SMS base configuration
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5.21 Creating ACS routines Storage
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5.22 DFSMS setup for z/OS IEASYSxx
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5.23 Starting SMS and activating a
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5.24 Control SMS processing with op
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5.25 Displaying the SMS configurati
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exception. If it is clear that a PD
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sets (see Figure 5-27 on page 287).
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Using a high level qualifier (HLQ)
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5.30 Establishing installation stan
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5.32 Data class attributes Data cla
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5.34 Simplifying JCL use Figure 5-3
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► The AVGREC attribute indicates
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Considerations when specifying spac
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5.38 SMS PDSE support SMS PDSE supp
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5.40 Allocating new PDSEs //ALLOC E
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Production batch refers to data cre
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tape are stored as a tape data set
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5.44 ISMF: Product relationships IS
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5.45 ISMF: What you can do with ISM
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5.46 ISMF: Accessing ISMF Panel Hel
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5.48 ISMF: Obtaining information ab
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5.49 ISMF: Data set option Figure 5
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5.51 ISMF: Management Class option
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5.53 ISMF: Storage Class option Fig
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6.1 Catalogs ICF structure 1 ICF st
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6.2 The basic catalog structure (BC
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6.3 The VSAM volume data set (VVDS)
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6.4 Catalogs by function SYSCAT VOL
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User catalogs The difference betwee
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Multilevel aliases You can augment
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Defining a cataloged data set When
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The example in Figure 6-9 on page 3
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6.8 Using multiple catalogs CATALOG
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If you need to share data sets acro
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► List a user catalog connector i
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Note: When you delete a data set, t
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DELET6 JOB ... //STEP1 EXEC PGM=IDC
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Note: The command will result in er
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You can later recover the backup co
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Aliases to the catalog can be defin
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► Physical errors The records on
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Because APF authorization is establ
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3. Use EXAMINE and DIAGNOSE to ensu
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5. Use REPRO MERGECAT to split the
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The two types of buffer are used to
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Catalog report output This MODIFY c
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Restarting the catalog address spac
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► MODIFY CATALOG,LIST The LIST co
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Recover from performance slow downs
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2. Define or alter your existing ca
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7.1 VSAM share options Share option
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7.2 Base VSAM buffering Three types
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7.3 Base VSAM locking Figure 7-3 Ex
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7.5 VSAM record-level sharing intro
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► Non-CICS jobs can have read-onl
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7.8 Buffering under VSAM RLS CICS R
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7.9 VSAM RLS locking control interv
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7.10 VSAM RLS/CICS data set recover
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7.11 Transactional recovery Commite
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7.13 VSAM RLS implementation Update
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Cache structures Coupling Facility
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7.15 Update PARMLIB with VSAM RLS p
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7.16 Define sharing control data se
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Tip: Place the SHCDSs on separate v
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Command ===> Figure 7-22 CF cache u
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7.18 Update data sets with log para
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7.19 The SMSVSAM address space RLS
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7.20 Interacting with VSAM RLS Inte
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To learn about other DISPLAY comman
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to use this specification or the sp
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► RECOVERY REQUIRED This field in
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DFSMStvs is a follow-on project/cap
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Like CICS, DFSMStvs does not perfor
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It is RRS that provides the means t
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7.27 Unit of work and unit of recov
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► Log of logs (optional, shared w
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7.30 Application considerations Bre
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7.31 DFSMStvs logging implementatio
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LABEL JOB ... //STEP10 EXEC PGM=IXC
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7.33 Update PARMLIB with DFSMStvs p
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7.34 The DFSMStvs instance CICSA R/
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Changes to parameters other than AK
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7.36 Summary Figure 7-48 Summary Ba
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8.1 Overview of DASD types Traditio
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8.2 Redundant array of independent
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8.3 Seascape architecture Powerful
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► Data copy sharing Data copy sha
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NVS cache NVS is used to store a se
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8.6 ESS major components Figure 8-6
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8.8 FICON host adapters FICON host
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8.9 ESS disks Eight-packs Set of 8
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8.10 ESS device adapters SSA 160 De
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8.11 SSA loops SSA operation 4 link
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8.12 RAID-10 RAID-10 configurations
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8.13 Storage balancing with RAID-10
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Peer-to-peer remote copy (PPRC) PPR
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8.15 ESS performance features Prior
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8.16 IBM TotalStorage DS6000 Enterp
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DS6000 expansion enclosure (Model 1
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support for one or two expansion fr
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The DS8300 models can support eithe
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consolidations where separate stora
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Copy Services include the following
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TotalStorage Expert helps storage a
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identifying the data set and descri
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Table 8-4 Types of labels Code Mean
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equired. Therefore, the resulting t
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Drive designed for automation solut
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3494 models and features IBM 3494 o
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Each FICON channel in the VTS can s
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In addition to the 3494 VTS compone
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► Consolidation Another benefit i
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Online resources ► z/OS DFSMShsm
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