Joined: 26 Nov 2002 Posts: 12378 Topics: 75 Location: San Jose
Posted: Sun Jan 04, 2004 11:49 am Post subject:
Ravikumar,
The answer is option A. Coding Unit=(,5) requests that the system assign 5 devices to the data set. The system obtains the device type from the catalog. You coded SPACE=(CYL,(5,2),RLSE) which means you will get upto (5 + (15 * 2) = 35) cylinders on each of the 5 volumes provided that you have that many volumes in the Storage group. So the max size would 5 * 35 = 175 cylinders. If there is not enough free space on the DASD volumes, you could get a lot less than 35 cyl per volume. check the DSLIST(3.4) and it would show the summary of the total space of a dataset across all extents on all volumes.
Joined: 04 Dec 2002 Posts: 71 Topics: 0 Location: Little Falls, NJ
Posted: Tue Jan 13, 2004 4:38 pm Post subject:
Actually the answer is B.
I seems that you are really asking "when the dataset is extended to a secondary volume, is the first allocate equal to the primary allocation, or the secondary allocation quantity?" The answer is the secondary quantity. The primary quantity is used only for the initial allocation on the first volume.
There are exceptions, such as SMS guaranteed space datasets, and extended format datasets. _________________ Bruce A. Black
Senior Software Developer
Innovation Data Processing
Joined: 07 Feb 2003 Posts: 266 Topics: 1 Location: Edison, NJ USA
Posted: Wed Jan 14, 2004 12:01 am Post subject:
Hi all,
I've always been under the impression that:
Code:
SPACE=(CYL,(5,2),RLSE),UNIT=(,5)
Results in 1*5 + 15*2 or 35 CYLs allocated to the file. If the SPACE request couldn't be satisfied on one volume, the remaining 4 volumes could be used to satisfy the request, but the total maximum would still remain at 35 CYLs not 175.
Additionally, if the primary space couldn't be satisfied in one contiuous extent, up to four additional exents could be used to satisfy the primary allocation. In that case the secondary allocation would be reduced by up to four extents correspondingly.
Did I have it wrong all these years? I checked the JCL book I have and don't see any reference that would have me beleive differently. If I've got it wrong please point me to the doc source that proves it.
Joined: 04 Dec 2002 Posts: 71 Topics: 0 Location: Little Falls, NJ
Posted: Wed Jan 14, 2004 1:04 pm Post subject:
Quote:
I've always been under the impression that:
Code:
SPACE=(CYL,(5,2),RLSE),UNIT=(,5)
Results in 1*5 + 15*2 or 35 CYLs allocated to the file. If the SPACE request couldn't be satisfied on one volume, the remaining 4 volumes could be used to satisfy the request, but the total maximum would still remain at 35 CYLs not 175.
This is from the IBM Using Data Sets manual
"You can allocate space for a multivolume data set the same as for a single
volume data set. DASD space is initially allocated on the first volume
only (exceptions are striped extended-format data sets and guaranteed
space data sets). When the primary allocation of space is filled, space is
allocated in secondary storage amounts (if specified). The extents can be
allocated on other volumes.
When a multivolume non-VSAM, non-extended-format data set extends to the next volume, the initial space allocated on that volume is the econdary
amount. "
The primary quantity (5 cyl in your example) must be allocated on the first volume, although it can be allocated in up to 5 extents if the volume is very fragmented (5 1 cyl extents in your example). It will extent it in 2 cyl increments on that volume until there are total of 16 extents on that volume. THEN it will go to a secondary volume and get space in 2 cylinder incrementals until that vol has 16 extents, etc _________________ Bruce A. Black
Senior Software Developer
Innovation Data Processing
Joined: 07 Feb 2003 Posts: 266 Topics: 1 Location: Edison, NJ USA
Posted: Wed Jan 14, 2004 8:07 pm Post subject:
Thanx guys,
I learned something new today. One ques, though:
I saw this
Quote:
1.3.3.2 Multivolume Non-VSAM Data Sets
When a multivolume non-VSAM, non-extended-format data set extends to the next volume, the initial space allocated on that volume is the secondary amount.
Wouldn't that make the total in our example 163 CYLs? Or did I miss something again?
Ques 2: If Vol1 runs out of space after 2 secondary allocations, how does allocation proceed from there?
The remaining 13 on Vol2, the next 16 on Vol3, etc.?
Or the remaining 13 on Vol2, the next 16 on Vol2, etc.? Don't really need an ans, just an idle thought.
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Don't really need an ans, just an idle thought.