ASSM Segment Extends in RAC Even if There is Free Space
(Doc ID 1601444.1)
Last updated on FEBRUARY 26, 2019
Applies to:
Oracle Database - Enterprise Edition - Version 10.2.0.3 to 11.2.0.3 [Release 10.2 to 11.2]Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.
***Checked for relevance on 01-Sep-2017***
Symptoms
ASSM segments may extend in RAC more than necessary under concurrent insert/update workloads.
dbms_space.space_usage output shows that unformatted and fs4 blocks were increasing.
.
Time part_name unformatted fs1 fs2 fs3 fs4 full
----------+------------------+-----------+-----+-----+-----+-------+-------+
15:03:14 | PT_00199_R200808 | 1984 | 19 | 21 | 31 | 475 | 1500 |
15:23:12 | PT_00199_R200808 | 2528 | 19 | 26 | 37 | 1581 | 1855 |
15:39:14 | PT_00199_R200808 | 3224 | 22 | 39 | 55 | 2618 | 2128 |
15:51:10 | PT_00199_R200808 | 4608 | 29 | 45 | 60 | 3051 | 2333 |
16:01:14 | PT_00199_R200808 | 5800 | 27 | 56 | 59 | 3712 | 2512 |
:
19:35:10 | PT_00199_R200808 | 44048 | 82 | 222 | 222 | 20609 | 6143 |
19:41:19 | PT_00199_R200808 | 45304 | 83 | 226 | 232 | 21275 | 6246 |
19:49:20 | PT_00199_R200808 | 46640 | 85 | 238 | 235 | 21829 | 6379 |
19:59:14 | PT_00199_R200808 | 47960 | 89 | 242 | 237 | 22369 | 6549 |
20:05:13 | PT_00199_R200808 | 49280 | 91 | 246 | 235 | 22981 | 6653 |
From the Bitmap dump we can observe following points:
- Number of full extents increase over time on both instances. It seems there are more activities from inst1.
- Number of free extents that has affinity with inst1 increases while free extents from inst2 decreases. Inst1 is stealing
a couple of extents from inst2.
Changes
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |