VSAM Faq's

Question: help i need information about files none vsam direct

Answer: i dont the answer

Question: How do you fix the problem associated with VSAM out of space condition?

Answer: 1. Define new VSAM dataset allocated with more space. 2. Use IDCAMS to REPRO the old VSAM file to new VSAM dataset. 3. Use IDCAMS to ALTER / rename the old VSAM dataset or se IDCAMS to DELETE the old VSAM dataset. 4. Use IDCAMS to ALTER / rename the new VSAM dataset to the name of the original VSAM dataset.

Question: What is the meaning of VSAM RETURN-CODE 28?

Answer: Out of space condition is raised.

Question: Correction to the previous question - Yor can have ALT INDEX only on KSDS and ESDS - not RRDS.

Answer: See the question for correction - you cannot have ALT INDEX for RRDS.

Question: How amny Alternate Indexes you can have on a dataset? - Remember ALT INDEX is possibleonly on KSDS and RRDS.

Answer: 255 - but you must be a nut to have so many ALT Indexes on a dataset!

Question: Is it slower if you access a record through ALT INDEX as compared to Primary INDEX?

Answer: Yes. Why? Because the alternate key would first locate the primary key, which in turn locates the actual record. Needs twice the number of I/Os.

Question: What is RECOVERY and SPEED parameters in DEFINE CLUSTER command?

Answer: RECOVERY (default) and SPEED are mutulally exclusive. Recovery preformats the control areas during the initial dataset load, if the job fails, you can restart but you must have a recovery routine already written to restart the job. SPEED does not preformat the CAs. It is recommended that you specify SPEED to speed up your initial data load.

Question: describe SHAREOPTIONS parameter (SHR) in Define Cluster command.

Answer: It defines the cross-region and cross-system sharing capabilities of the dataset. Syntax is SHR(CRvalue CSvalue) value 1 means multiple read OR single write (read integrity) 2 means multiple read AND single write (Write integrity) 3 means Multiple read AND multiple write 4 is same as 3, which refreshes the buffer with every random access. default is SHR(1 3).

Question: What does the KEYRANGES parmater in Define Cluster commend do?

Answer: It divides a large dataset into several volumes accoring to the Keyranges specified. e.g., KEYRANGES ((0000001 2999999) (3000000 5999999)). if the activity on the key ranges are evenly distributed, cuncurrent access is possible, which is a performance improvement.

Question: What are the optional parameters to the input dataset While loading the empty cluster with the data records?

Answer: 1)FROMADDRESS(address) 2)TOADDRESS(address) where 'address' specifies the RBA value of the key of the input record. 3)FROMNUMBER(rrn) 4)TONUMBER(rrn) where 'rrn' specifies the relative record number of the RRDS record 5)FROMKEY(key) 6)TOKEY(key) where 'key' specifies the key of the input record 7)SKIP(number) 8)COUNT(number) where 'number' specifies the number of records to skip or copy Ex: REPRO INFILE(DD1) OUTFILE(DD2) SKIP(9000) COUNT(700) - Skips the first 9000 records and begins copying at 9001 and copies 700 records from DD1 to DD2.

Question: What is GDG means in VSAM???

Answer: Generation Data Group

Question: What is GDG means in VSAM???

Answer: I don't know

Question: What is IDCAMS? and what is the purpose of it?.

Answer: IDCAMS is an access method services utility used for creating, deleting, altering VSAM files and copying sequential file to a VSAM file, etc.

Question: How to delete a member using JCL.

Answer: Using IDCAMS a member can be deleted. DELETE 'XXX.YYY(member)

Question: What is the Difference between LDS & ESDS ?

Answer: These two datesets are VSAM datasets. ESDS maintains control information. But LDS does not maintains the control information.

Question: A. Is a delete operation possible in an ESDS?B.Is rewrite operation possible in ESDS ?

Answer: A. No delete operation is not possible in VSAM ESDS.B. Yes rewrite operation is possible in an ESDS.

Question: What is an alternet index and path ?

Answer: An alternet index is an another way of accessing key sequenced data record stored in a base cluster and path is the linkage which connect alternet index to its base cluster.

Question: How many buffers are alloted to VSAM KSDS and ESDS?

Answer: Ans:2 data buffers by default for ESDS.for KSDS it allots 2 data buffers and 1 index buffers. each buffer is about 4k.

Question: what's the biggest disadvantage of using a VSAM dataset?


Question: what's the device independent method to indicate where a Record is Stored?

Answer: The answer is : By USING RBA(Relative Byte Address).


Answer: A: 122 TIMES

Question: what is the RRN for the first record in RRDS?

Answer: The answer is : 1

Question: what is a Base Cluser?

Answer: The Index and data components of a KSDS

Question: If fspc(100 100) is specified does it mean that both the control interval and control area will be left empty because 100 % of both ci and ca are specified to be empty?

Answer: no,they would not be left empty.one record will be written in each ci and 1 ci will be written for each ca.

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