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upendrasri
Active User
Joined: 28 Sep 2017
Posts: 124
Location: India
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Hi All,
I would like to understand the deffence between Voume count and Dynamic volume count in ISMF Dataclass?
I have gone through DFSMSdfp Storage Administration mauals.
Volume count is the maximum number of volumes which dataset can expand.
Dyanamic volume count is the maximum number of volumes which can be added dynamically to a dataset.
Both Volume count + Dynamic Voulme count should not cross 59 volumes.
See the below example.
One of my old dataset : TTSS.Z120.TEST --> This is a VSAM Multivolume dataset.
From File Aid(And LISTC also shows same information) using Dataset Utility option we can see the below details.
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DATA COMPONENT: 'TTSS.Z120.TEST.DATA'
Volume Allocations:
1. A4N138 2. A4N204 3. A4N12A 4. A4N1B6 5. A4N121
6. A4N1FE 7. A4N115 8. A4N1CE 9. A4N1G3 10. A4N208
11. A4N167 12. * 13. * 14. * 15. *
16. * 17. * 18. * 19. * 20. *
21. * 22. * 23. * 24. * 25. *
26. * 27. * 28. * 29. * 30. *
31. * 32. * 33. * 34. * 35. *
36. * 37. ______ 38. ______ 39. ______ 40. ______
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Current dataset Used volumes : 11
Total Available volumes for this dataset : 36
From Listc of the above dataset
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CLUSTER ------- TTSS.Z120.TEST
IN-CAT --- USER.TEST.CATALOG
HISTORY
DATASET-OWNER-----(NULL) CREATION--------2017.337
RELEASE----------------2 EXPIRATION------0000.000
SMSDATA
STORAGECLASS ---STANDARD MANAGEMENTCLASS--PRDINS1
DATACLASS ------EXTEND30 LBACKUP ---0000.000.0000
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From ISMF DATACLASSE EXTEND30 we can see the below details.
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TEST1 DATA CLASS LIST
Command ===> Scroll ===> HALF
Entries 1-1 of 1
Data Columns 12-16 of 52
CDS Name : ACTIVE
Enter Line Operators below:
LINE DATACLAS SPACE RETPD OR VOLUME ADDITIONAL DYNVOL
OPERATOR NAME DIRECTORY EXPDT COUNT VOLUME AMT COUNT
---(1)---- --(2)--- --(12)--- ---(13)--- -(14)- ---(15)--- -(16)-
EXTEND30 ------ ---------- 1 --------- 30
---------- -------- ------ BOTTOM OF DATA ------ -------- ----------
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As per ISMF Maximum number of volumes available for this dataset is 1 + 30 ---> 31 ----> correct me if I am wrong?
But currently as per File Aid Maximum available number of volumes for this data set is 36
is it like after reaching Maximum 31 volumes , Manually 5 dynamic volumes added to this data set? |
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expat
Global Moderator
Joined: 14 Mar 2007
Posts: 8796
Location: Welsh Wales
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Excuse me, but what the hell has this question have to do with CLIST or REXX ???
Please learn to think about WHERE you post anything before you post it
Because I have to think about where I have to move it to 
How many volumes are defined to the storage group |
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upendrasri
Active User
Joined: 28 Sep 2017
Posts: 124
Location: India
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Hi Expat,
Sorry, One of my forum is open and I just thought of starting a new topic and posed from there... didn't observe that am in Rexx forum.
There are 110 volumes defined in Storage Group.
If you want am okay to open a new topic outside CLIST or Rexx forum.
Thanks. |
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Pete Wilson
Active Member
Joined: 31 Dec 2009
Posts: 592
Location: London
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Volume Count is the number of volumes the dataset is initially allocated on.
Dynamic Volume Count is invoked if the initial volumes are full and the dataset needs to extend further, at which time the extra 'candidate' volumes (those showing as an asterisk) are added by DVC. The candidate volumes are converted to real volumes as the dataset extends to an extra volume.
DASD datasets cannot have more than 59 volumes as you say. So Volume Count and Dynamic Volume count cannot exceed that, but can be less and that lesser figure becomes the limit.
Also be aware that for every volume whether candidate or real uses about 4k of the TIOT so if you have the numbers too high you can run out of TIOT space which is only 64k, especially if there's a lot of DD's in your job as well. If you have XTIOT enabled it's less of an issue. |
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Robert Sample
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Joined: 06 Jun 2008
Posts: 8700
Location: Dubuque, Iowa, USA
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If you use the online help on the ISMF screen, you will find it explicitly stated that the Data Class DYNVOL COUNT value can be overridden with JCL or other allocation methods, and overrides will not appear in the data column.
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| is it like after reaching Maximum 31 volumes , Manually 5 dynamic volumes added to this data set? |
No, the actual behavior will depend upon what your JCL allocates. You can still use up to 59 volumes for a single data set. |
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Pete Wilson
Active Member
Joined: 31 Dec 2009
Posts: 592
Location: London
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| you can also do IDCAMS ALTER dsn ADDVOLUMES(* * *) to add more candidate volumes for existing datasets |
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