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Q: How to extend VSAM file?
Answer:
ALTER ds.name ADDVOLUMES(vol). Or secondary allocation triggers extension. RECORDS/CYLINDERS secondary amount. Up to 255 extents per volume. May need to reorganize if fragmented.
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Q: What is KEYRANGES?
Answer:
KEYRANGES distributes KSDS across volumes by key value. KEYRANGES((low1 high1) (low2 high2)). Each range on different volume. Improves parallel access. Rarely used now.
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Q: Explain IDCAMS ALTER command
Answer:
ALTER modifies cluster attributes. ALTER ds.name ADDVOLUMES(vol). ALTER ds.name SHAREOPTIONS(2 3). Some changes need empty file. Some need unload/reload. Limited modifications.
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Q: Explain LOAD utility
Answer:
LOAD inserts large data volumes. LOAD DATA INTO TABLE name. Options: REPLACE, RESUME, LOG NO. Input is SYSREC dataset. LOAD faster than INSERT. Puts tablespace in COPY PENDING after LOG NO.
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Q: Explain storage group
Answer:
Storage group defines volumes for data. CREATE STOGROUP name VOLUMES(vol1, vol2). Tablespaces assigned to stogroups. DB2 manages space within. PRIQTY/SECQTY control allocation. Foundation of storage management.
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Q: What is ORDERED attribute?
Answer:
ORDERED on DEFINE allocates volumes in specified order. Without ORDERED, system chooses. ORDERED ensures predictable allocation. May be important for performance tuning.
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Q: What causes S322 abend?
Answer:
S322 is job/step time exceeded. Check TIME parameter on JOB/EXEC. Causes: infinite loop, too much data, insufficient time allocated. Fix: increase TIME, optimize program, check data volumes. TIME=1440 is no limit (24 hours).
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Q: How to resize VSAM?
Answer:
Cannot resize directly. REPRO out, DELETE, DEFINE larger, REPRO back. Or ALTER to add secondary space/volumes. Planning important - define adequate size initially.
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Q: What is UNIT parameter?
Answer:
UNIT specifies device type. UNIT=SYSDA (direct access), UNIT=TAPE, UNIT=3390. UNIT=AFF=ddname shares device. UNIT=(SYSDA,2) allocates 2 volumes. SMS may override. UNIT=VIO for virtual I/O (memory only).
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Q: What is VOL parameter?
Answer:
VOL specifies volume. VOL=SER=PACK01 specific volume. VOL=REF=*.STEP.DD copies volume from previous. VOL=(,RETAIN) keeps volume mounted. VOL=(,,,5) allows 5 volumes. SER overrides SMS placement. Use cautiously.
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Q: How to handle multivolume datasets?
Answer:
VOL=(,,,n) allows n volumes. SPACE with volume count. SMS handles multivolume automatically. DISP=MOD extends to new volume. DATACLAS can specify multivolume. Large datasets need multivolume planning.
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Q: What causes S837 abend?
Answer:
S837 is end of volume and no more volumes available. Dataset needs more space. Solutions: allocate larger primary/secondary, increase volume count, extend dataset. IEFBR14 can extend with MOD DISP.