Dynamic extend questions
Article ID: 273357
Updated On:
Products
Issue/Introduction
I've been using the dynamic extend feature under our Datacom/AD regions for various databases and indexes. Today when I extended some files, I received this informational message:
CA11MUFP:DB01311I - DYNAMIC_EXTEND 601,JHF,300,CYL
CA11MUFP:DB01335I - CONSOLE SCHEDULED - DYNAMIC_EXTEND 601,JHF,300,CYL
CA11MUFP:DB01705I - DYNAMIC EXTEND START JHF601 TRK 112,500 CAI.DATACOM.PRDPLX03
CA11MUFP:DB01706I - DYNAMIC EXTEND END JHF601 TRK 117,000 JSY0BF VOL 3 VOLS 3 EX
CA11MUFP:DB01311I - DYNAMIC_EXTEND 601,DSN,500,CYL
CA11MUFP:DB01335I - CONSOLE SCHEDULED - DYNAMIC_EXTEND 601,DSN,500,CYL
CA11MUFP:DB01705I - DYNAMIC EXTEND START DSN601 TRK 111,480 CAI.DATACOM.PRDPLX03
IGD17296I DYNAMIC VOLUME COUNT (DVC=25) WAS USED TO 310
EXTEND DATA SET CAI.DATACOM.PRDPLX03.CA11.DSN601
CA11MUFP:DB01706I - DYNAMIC EXTEND END DSN601 TRK 118,980 JSY097 VOL 4 VOLS 4 EX
CA11MUFP:DB01311I - DYNAMIC_EXTEND 601,IXX,400,CYL
CA11MUFP:DB01335I - CONSOLE SCHEDULED - DYNAMIC_EXTEND 601,IXX,400,CYL
CA11MUFP:DB01705I - DYNAMIC EXTEND START IXX601 TRK 103,500 CAI.DATACOM.PRDPLX03
IGD17296I DYNAMIC VOLUME COUNT (DVC=25) WAS USED TO 352
EXTEND DATA SET CAI.DATACOM.PRDPLX03.CA11.IXX601
CA11MUFP:DB01706I - DYNAMIC EXTEND END IXX601 TRK 109,500 JSY062 VOL 3 VOLS 3 EX
Is this telling me that I can't do any more dynamic extends, and need to do some DBA function? If so, just what would that DBA function be?
Environment
Release : 15.1
Component : Datacom/AD
Component : Datacom/DB
Cause
This is an SMS informational message about the DataClass in use.
Resolution
Here are the messages extracted from the log above:
IGD17296I DYNAMIC VOLUME COUNT (DVC=25) WAS USED TO
EXTEND DATA SET CAI.DATACOM.PRDPLX03.CA11.DSN601
IGD17296I DYNAMIC VOLUME COUNT (DVC=25) WAS USED TO
EXTEND DATA SET CAI.DATACOM.PRDPLX03.CA11.IXX601
Here is the explanation from the IBM z/OS MVS System Messages Vol 8 (IEF-IGD) documentation:
Explanation
Dynamic Volume Count (DVC) is specified in the data class with a value of n and used during allocation processing. DVC has significance only when it is larger than the specified volume count. SMS attempted to allocate a new data set or extend an existing data set to a new volume using the DVC, which is used only after the data set reaches the current volume count.
In the message text:
n = A number from 1 to 59
dsn = The data set name
System action
The system continues processing.
System programmer response
Review volume count and determine if DVC is entered as expected. DVC may be entered in cases such as a low volume count is specified for the data set or the allocation needs more volumes due to space constraints.
Programmer response
Review volume count and determine if DVC is entered as expected. DVC may be entered in cases such as a low volume count is specified for the data set or the allocation needs more volumes due to space constraints.
Source
Storage Management System (SMS)
As I understand it, the DVC (dynamic volume count) is the maximum number of volumes that you have that can be added to a file (beyond the initial volumes used when the file was created) when it is dynamically extended. This was introduced with z/OS 2.2 with this explanation of DVC:
DVC is a field in the data class that defines the maximum number of volumes that data set can span and is used during the allocation or extend processing if the specified volume count is not sufficient. This new message allows the user to take preventive actions for potential space failures.
If you review the file allocation info for CAI.DATACOM.PRDPLX03.CA11.DSN601 and CAI.DATACOM.PRDPLX03.CA11.IXX601, you should be able find the DataClass used on these files. You can then go to ISMF and in the Data Class function, you should be able to see how this DataClass is defined.
As this has nothing to do with Datacom processing, there is no DBA function to perform. If you have further questions, you should contact your Storage Management team and they can explain this to you further. Since you are only on volumes #3 and #4, and you have at least 26 total volumes available (the DVC=25 from the message plus the initial 1 or more), you should have no problems with the automatic or directed dynamic extends.
Additional Information
As always, please contact Broadcom support for Datacom if you have further questions.
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