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socker_dad
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Joined: 05 Dec 2006
Posts: 177
Location: Seattle, WA
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This is a basic question, but one we're struggling with, so I beg patience up front!
We are experiencing slow performance in one of our CICS regions and one of the messages the log file keeps getting is this:
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AL$0001I CICP6235, CICP6, LC4070IB, , MIPS235.P.C4070IB.DATA.VSAM
AL$ESD1E DATA SET IS ON MAXIMUM VOLUMES TERMINATING RECOVERY
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I can see that this is a KSDS Ext-Addr file in File-Aid, but I'm not sure what else I should be looking for. The Current space allocated/used ratio is 69% (38,985 tracks/26,821 tracks), which doesn't seem like a bad ratio. The KSDS Index is 125 tracks. The total Data Records is 423,867, but the Retrieved Data Records is 14,226,052.
One thing I noted is that this VSAM file gets copied to a flat file daily, but is never deleted/redefined/reloaded like other VSAM files that I've seen. Could that be the source of the performance 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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I'd want to see a LISTCAT for the data set, and I'd be looking particularly at things like CI splits, CA splits, number of volumes in use, number of candidate volumes, number of extents per volume, HI-A-RBA and HI-U-RBA. The error message number you quoted is NOT a standard IBM error message number, so one place to start would be to find out what is generating the message and what that software says about that particular error message.
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| The Current space allocated/used ratio is 69% (38,985 tracks/26,821 tracks) |
This may be a completely misleading number -- if the data set needs to add records (either at the end of the data set or through a split), the LISTCAT values may indicate that such an extension is not possible for one reason or another.
One quick-and-easy possible solution would be to unload the VSAM, delete / define it, and reload it. Comparing the LISTCAT from before this is done to the LISTCAT after this is done should shed some light on the situation. |
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socker_dad
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Joined: 05 Dec 2006
Posts: 177
Location: Seattle, WA
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The delete/define/reload sounds like the best to me as well. I'll work on getting permission for it. In the meantime:
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Data Component Information: Current Allocation Options:
Device type: 3390 Load option: SPEED
Organization: KSDS EXT-ADDR Write check: NO
KSDS key length: 14 Buffer space: 18432
KSDS key location: 0 Erase on delete: NO
Average record size: 600 Imbedded index: NO
Maximum record size: 16309 Replicated index: NO
Allocated Space: Unit Primary Secondary Reuse option: NO
Data: CYLINDERS 599 50 Share option: 2-3
Index: TRACKS 29 3 Spanned records: YES
Dataset Date Information: Key ranges present: NO
Creation date: 28/07/2019 AIX-unique keys:
Expiration date: AIX-upgrade:
Modification date: 18/08/2019
Modification time: 01:00 AM GMT Owner ID:
CLUSTER - MIPS235.P.C3800IA.DATA.VSAM Storage: CICSPROD
Data: VSAM
Management: NOMIG
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - -
Current Space: ALLOCATED USED Data Records
Tracks: 38985 26821 ( 69 %) Total: 423,867
Extents: 15 5 ( 33 %) Deleted: 0
KSDS Index: 125 - Inserted: 129174
Updated: 0
Allocation Type: UNIQUE Retrieved: 14226052
RRDS: Max record number: 0 KSDS: Index Records: 2522
- - - - - - - - - Current Reorganization Information - - - - - - - - - - - - -
INDEX DATA Index Statistics:
Number of CA splits: 9 1074 Number of levels: 3
Number of CI splits: 1074 31741 Entries per section: 9
CI Size: 2048 8192 First sequence-set RBA: 0
Number of CIs/CA: 21 90 Volume Information:
Free CIs/CA: 0 13 Physical record size: 8192
Percent free CIs/CA: 0 15 Records per track: 6
Percent free bytes/CI: 0 25 Tracks per CA: 15
DATA COMPONENT: 'MIPS235.P.C3800IA.DATA.VSAM.PRIME'
Volume Allocations:
1. CP9106 2. * 3. * 4. * 5. *
6. ______ 7. ______ 8. ______ 9. ______ 10. ______
11. ______ 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. ______
41. ______ 42. ______ 43. ______ 44. ______ 45. ______
46. ______ 47. ______ 48. ______ 49. ______ 50. ______
51. ______ 52. ______ 53. ______ 54. ______ 55. ______
56. ______ 57. ______ 58. ______ 59. ______
INDEX COMPONENT: 'MIPS235.P.C3800IA.DATA.VSAM.INDEX'
Volume Allocations:
1. CP9106 2. * 3. * 4. * 5. * 6. ______ 7. ______
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I didn't see any stats on # candidate volumes, extents per volume, HI-A-RBA and HI-U-RBA. I was wondering about that error message: I hadn't seen one like that before. |
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Robert Sample
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Location: Dubuque, Iowa, USA
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What you posted isn't really a LISTCAT, but it has almost all the relevant data anyway.
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DATA COMPONENT: 'MIPS235.P.C3800IA.DATA.VSAM.PRIME'
Volume Allocations:
1. CP9106 2. * 3. * 4. * 5. * |
The * means that it is a candidate volume. So the data set is on one volume. Splits don't have the performance impact that they did when disks were physically moving read/write heads from track to track, but 31741 CI splits and 1074 CA splits definitely means your data is scattered (especially considering the data set is only 3 weeks old). In a batch application, that usually doesn't matter but it can mean a performance hit to a CICS application, depending upon the read method (sequential or direct). Another factor to consider is the spanned records -- I don't recall ever hearing if spanned record access would be slower than non-spanned records, but I certainly think it is possible (since for the spanned records, 2-3 data CI have to be read not 1).
With a 25% CI freespace, you are getting about 10 records per CI based on the average record length, and 900 per CA. The data requires just over 540 cylinders and the used space is 1789 cylinders. I definitely think an unload, delete / define, reload is recommended. It will probably help the CICS performance as well, although CICS performance depends upon so many factors that it is hard to say for sure. |
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Rohit Umarjikar
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Joined: 21 Sep 2010
Posts: 3109
Location: NYC,USA
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| One thing I noted is that this VSAM file gets copied to a flat file daily, but is never deleted/redefined/reloaded like other VSAM files that I've seen. |
We have same process today unloading to PS everyday but I shall check if we do deleted/redefined/reloaded.
This might clue you more options to look for.
CICS VSAM and file control: Performance and tuning
Since, LSR/NSR/BLSR consideration changes batch performance, So that might also impact in online and can be investigated accordingly. |
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