Are you overwhelmed by the growing amount of data in your environment? Are you maximizing application availability? As the number of tables with billions of rows continues to grow, so do the management challenges. In this session, we will discuss the challenges and solutions for optimum availability and performance, with techniques to efficiently and effectively manage very large amounts of data.

1. IBM Software Group
DB2 10 for z/OS;Breaking
Barriers and Beyond
Designing for
Advanced Availability
and Scalablity
© 2010 IBM Corporation

2. Migration Planning Workshop
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2 © 2010 IBM Corporation

3. Migration Planning Workshop
Focus on avoiding outages and “show stoppers”
Availability Scalability
To be able to make changes to the To avoid outages caused either by
subsystem or member without system or object size limits
causing an system outage
– TS physical limits(Segmented
– CDB updates(add another
DB2 server) TS 64g limit;Partition DSSIZE
limit(PM42175) )
– DDF/TCPIP member
subsetting – Workfile sort record cannot
– Log RBA/LRSN limit span pages(32k) limit-sort
reached(DB2 11) key limit(16k)
– Add active log – RID pool failures causing TS
To be able to make changes to DB2 scans
objects without causing an object To avoid DB2 outages caused by
outage(read or read write) Virtual Storage Constraint
– Rename or drop(DB2 11) a – 64 bit addressing
column
– Migrate to UTS from PTS or – Increase number of active
segmented threads by a factor of 10
– Alter Limit Key(DB2 11) – New Storage zparms to avoid
– Online-Reorg the runaway DB2/LPAR shutdown
Catalog/Directory
3 © 2010 IBM Corporation

4. Migration Planning Workshop
DB2 10 Virtual Storage Constraint Relief-Scalability
DB2 10
DBM1 below 2GB Global DSC
CT/PT
– 75-90% less usage in DB2 10
compared to DB2 9 DBD
– Some of working storage (stack, Local DSC
xproc storage) stays below 2GB SKCT
Thread / Stack SKPT
Larger number of threads
– Possible data sharing member
consolidation Thread / Stack/ working storage
Improve CPU with storage 75-90% less usage
– More release deallocate DBM1 below bar
– Larger MAXKEEPD values for after REBIND
KEEPDYNAMIC=YES
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5. Migration Planning Workshop
Availability:Managing DB2 Storage and avoiding DB2
outage
Real storage
– Need to carefully plan, provision and monitor real storage
consumption even in DB2 10
– Prior to V10 a hidden zparm SPRMRSMX (‘real storage kill switch’)
existed
• SPRMRSMX prevents a runaway DB2 subsystem from taking the
LPAR down
– Should be used when there is more than one DB2 subsystem
running on the same LPAR
– Aim is to prevent multiple outages being caused by a single
DB2 subsystem outage
– Should to set to 2x normal DB2 subsystem usage
– Kills the DB2 subsystem when SPRMRSMX value reached
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6. Migration Planning Workshop
Availability:Managing DB2 Storage and avoiding a DB2
outage cont..
• SPRMRSMX hidden zparm now becomes an opaque parameter
REALSTORAGE_MAX
• Will also introduce DISCARD mode to contract storage usage to protect against excessive
paging and use of AUX
– New zparm REALSTORAGE_MANAGEMENT controls when DB2 frees
storage frames back to z/OS
> ON -> Discard unused frames all the time - discard stack, thread storage, keep
footprint small
> OFF -> Do not discard unused frames unless things are getting out of hand
> AUTO (default) -> Detect whether paging is imminent and try to reduce the frame
counts to avoid system paging
– With AUTO, DB2 monitors paging rates, switches between ON/OFF and decides
when to discard frames based on
> 80% of SPRMRSMX reached
> 50% of AUX (ENF55 condition) used
> Hitting AVQLOW (available real storage frame)
– New messages (DSNV516I, 517I) for when paging rate thresholds cause DB2 to free
real frames
• Strong recommendation to apply PTF for APAR PM24723 before going into business
production and to run with REALSTORAGE_MANAGEMENT=AUTO
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7. Migration Planning Workshop
Other Availability & Scalability Improvements
Reduced latch and lock contention
– Improved efficiency for latch suspend/resume
– UTSERIAL lock elimination
New access currently committed option for readers to avoid
waiting for inserters or deleters
Use 64-bit common storage to avoid ECSA constraints
DB2 10 NFM catalog restructure improves BIND / Prepare
concurrency
Remove SPT01 64Gb constraint (inline LOB’s and
Compression)
Improved accounting rollup, compress SMF option
– Reduced SMF data volume
Lower overhead for very large buffer pools
Group Bufferpool write-around protocol enablement for
heavy group buffer pool write pageset(DB2 11)
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Migration Planning Workshop
Major changes in DB2 10 catalog & directory
Improve availability and productivity
Increase maximum size substantially
Reduce contention: BIND, Prepare, Utilities
– DDL concurrency also improved from removal of
DBD01 hash anchor locks
Catalog changes: Remove links, hashes
– Many more table spaces, partition by growth
– Row level locking, reordered row format
– CLOB and BLOB columns for long strings
o Inline for performance
– Online reorganization and check
– More automatic: DB2-managed SMS-controlled
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9. Migration Planning Workshop
Recent System APARs
DDF Availability Enhancements
– Change DDF location alias names online
o New MODIFY DDF ALIAS command
o New “dynamic alias” concept in addition to
existing 8 static aliases
– Online DDF CDB changes
o LOCATIONS, IPNAMES, IPLIST
– PM26480 (V10)
Ability to SELECT from SYSLGRNX
– PM35190 & PM42331 (V10)
– ISO(UR) enforced
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10. Migration Planning Workshop
Business value of Advanced Design-Pending Alters
Availability
– REORG with share level reference or change to move your
simple table spaces to new universal table spaces
– Move a segmented table space at the 64GB limit seamlessly
into a partition by growth table space without an outage
(aside from the rebinds)
Productivity
– Have DB2 materialize online ALTERs at DBA’s discretion at
a future date
– No need to CREATE new table spaces, UNLOAD/LOAD,
GRANT, DROP, REBIND
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Universal Table Spaces
What kind of Table Space will be created? (* optional)
CREATE SEGSIZE NUMPARTS MAXPARTITIONS Comments
TABLESPACE...
*SEGSIZE is optional.
Segmented
* Default for explicitly
created TS & implicitly
created TS for CM8.
SEGSIZE defaults to 4.
Default for DB2 9 NFM
UTS PBG with implicitly created
* TS.
Single table TS.
*SEGSIZE will default to
32.
Single table TS
UTS PBR *SEGSIZE will default to
* 32.
Partitioning TS prior to
Classic * V9
*SEGSIZE 0 will create
classic partitioned and
Partitioned TS CM8 behavior is same as
v8 NFM
11 © 2010 IBM Corporation
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Improved availability ALTER…
Classic Partitioned
Table Space Range-Partitioned
See APAR UTS PBR
PM25648
Single-Table
Segmented
Table Space
Hash
Single-Table
Simple Partition-By-Growth
Table Space UTS PBG
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13. Migration Planning Workshop
Possible online schema changes for TS and IX
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14. Migration Planning Workshop
Improved ALTER…
Pending changes materialized with an online REORG apply to UTS
– SEGSIZE – no other pending ALTERs can be done before this is materialized
– DSSIZE – no other pending ALTERs can be done before this is materialized
(IMPDSSIZE ZParm for default)
– MEMBER CLUSTER – new for UTS
– MAXPARTITIONS
• If other pending changes are involved, or changing table space type: it is pending
• Otherwise it is immediate
– Page Size (BUFFERPOOL)
• Can be done with REORG TABLESPACE (for indexes and tables) or REORG INDEX for only index
changes
Other ALTERs are immediate MAXPARTITIONS
– The above statements if TS or IX not defined
– MAXPARTITIONS (unless changing TS)
– BUFFERPOOL PGSTEAL NONE
– LOB INLINE LENGTH LOB
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Online Schema – Details on Execute ALTER Statement
Statement is validated
– Semantic checking against effective catalog definition
Assuming all checks out ok:
– Statement is put on pending list
– Table space is placed in Advisory-REORG pending :AREOR (non-restrictive)
• Not to be confused with REORG-pending advisory (AREO*) which says access path
could be degraded
– Statement completes with SQLCODE +610 to advertise the advisory state
Drop changes
– ALTER TABLESPACE… DROP PENDING CHANGES
• still in AREOR
• all changes for that table space will be dropped
SYSIBM.SYSPENDINGDDL:
DBNAME TSNAME DBID PSID OBJSCHEMA OBJNAME OPTION_ OPTION_ STATE
… KEYWORD VALUE
… MENT_
TEXT
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Online Schema – Details on Online REORG
Pending DDL is materialized - DSNU1163I
– Catalog is updated with the new attributes
– OBD is updated with the new attributes
– Data sets are updated with the new attributes
– Materialized SYSPENDINGDDL entries are removed
Stats are collected
– Default is TABLE ALL INDEX ALL UPDATE ALL HISTORY ALL unless
overridden
– Warning message is issued to indicate that some partition statistics may no
longer be accurate - DSNU1166I
• (COLGROUP, KEYCARD, HISTOGRAM …)
SYSCOPY entries show inability to recover object prior to changes
AREOR state is reset
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Online Schema…
Restrict RECOVER across materializing REORGs(some
availability in DB2 11)
Alter
MEMBER DML activities
CLUSTER
On REORG converts to Member RECOVER to
Cluster structure with In-line copy Currency
Image copy + log records
Plans and packages are invalidated if
– When changing the MAXPARTITIONS attribute of a simple
or segmented table space to convert it to a partition-by-
growth universal table space
– The SEGSIZE attribute of a partitioned table space is
changed to convert the table space to a range-partitioned
universal table space
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Member Cluster speed
Clustering
MEMBER CLUSTER added to UTS
– Avoid hotspots, P-lock, and page latch contention
• Usually only applicable for data sharing, concurrent access
• Each member is assigned a set of space map pages
• Ignores clustering index on insert, REORG to get clustering back
• Space map covered 199 data pages in DB2 9
• Space map covers 10 segments in DB2 10
– New column SYSTABLESPACE.MEMBER_CLUSTER
– LOCKSIZE row and larger page size may work better
– Very important for APPEND tables (DB2 9)
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DB2 10 Range Defined Table Spaces
---------------------------------- Random Inserts --------------------------------
Throughput CPU Time
PLL RLL PLL RLL
25000 1.2
1
Msec / Commit
20000
Rows/Sec
0.8
15000
0.6
10000 0.4
5000 0.2
0 0
PTS PTS/MC PBR PBR/MC PTS PTS/MC PBR PBR/MC
-------------------------------- Sequential Inserts --------------------------------
Throughput CPU Time
PLL RLL PLL RLL
120000 20
100000
Msec / Commit
15
Rows/Sec
80000
60000 10
40000
5
20000
0 0
PTS PTS/MC PBR PBR/MC PTS PTS/MC PBR PBR/MC
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20. Migration Planning Workshop
DB2 10 Non-range Defined Table Spaces
---------------------------------- Random Inserts --------------------------------
Throughput CPU Time
PLL RLL PLL RLL
25000 1.2
Msec / Commit
1
20000
Rows/Sec
0.8
15000
0.6
10000
0.4
5000 0.2
0 0
SEG PBG PBG/MC SEG PBG PBG/MC
-------------------------------- Sequential Inserts --------------------------------
Throughput CPU Time
PLL RLL PLL RLL
120000 25
100000
Msec / Commit
20
Rows/Sec
80000
15
60000
10
40000
20000 5
0 0
SEG PBG PBG/MC SEG PBG PBG/MC
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21. Migration Planning Workshop
Compress on INSERT
Data compression occurs when a dictionary exists
Prior to DB2 10
– Dictionary not built on a table space with COMPRESS YES attribute
until:
• REORG or
• LOAD utility was executed
– For some customers, REORG or LOAD are not executed frequently
– LOAD COPYDICTIONARY offered in DB2 9
DB2 10 NFM allows for build of compression dictionary on:
– INSERT
– MERGE
– LOAD utility with REPLACE, RESUME NO, or RESUME YES SHRLEVEL
CHANGE, and without KEEPDICTIONARY
Eliminate need for REORG or LOAD needed to build compression dictionary
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22. Migration Planning Workshop
How Compress on INSERT works
INSERT, MERGE and LOAD trigger the creation of a compression
directory if:
– The table space or partition is defined with COMPRESS YES
– The table space or partition has no compression dictionary built
– Inserted data reaches a threshold that allows the build of the
compression dictionary
If threshold is reached, dictionary build is done asynchronously
– Data continues to be inserted uncompressed until dictionary is ready
No way to turn off Compress on insert
– Use COMPRESS NO if unwanted
– DSNU235I – dictionary not built
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23. Migration Planning Workshop
Location of compression dictionary pages
If the dictionary pages are scattered throughout table a DSNU1232I -
REORG or COPY SYSTEMPAGES(YES) is needed to COMPRESSED
UNLOAD rows ROW
IS IGNORED
BECAUSE THE
H SM D D .. DICTIONARY IS
COPY TS... ..
H SM D D .. D D D D NOT AVAILABLE
SYSTEMPAGES
.. NO FOR TABLE
D D D D D DI D DI table-name
D DI D DI
COPY TS...
SYSTEMPAGES ..
Dictionary pages YES ..
(option makes H SM DI DI
not necessarily
after space map page! DB2 copy the
D D D D
dictionary pages
-Could use inline
after space map D D D
COPY during REORG
page)
To ensure dictionary
pages up front
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24. Migration Planning Workshop
Extended Address Volumes
Continue the direction started with the 3390-54 of defining larger
volumes by increasing the number of cylinders beyond 65520
in z/OS V1R10 and higher to support 262,668 cylinders
New track address format(CCCCHHHH-CCCCcccH)
– Continue relief provided by PAV, HyperPAV
– Benefit: 54 GB
• Increased z/OS addressable disk storage-supports SMS and non_SMS Max cyls: 65,520
• Easier to manage flash enabled devices for recover 3390-54
• Caution – small data sets may grow faster due to larger allocation in chunks of 21 cyls
Extended Addressing is needed for any DB2 dataset larger than 4GB
– Catalog and directory must belong to EA SMS
Size limited to
STOGROUP 223 GB
(262,668 Max
– Previously ‘LARGE’ datasets limited to 4GB, DSSIZE is cylinders)
now preferred method of defining size in z/OS V1R10
– Still have 64GB limit on dataset(DSSIZE) 3390-A
“EAV”
Up to 225 TB
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EAV DB2 Enablement
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26 © 2010 IBM Corporation