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Problem IT38686
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Status: Closed |
Db2 write performance on Linux might be affected due to file system journal waits
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| product: |
DB2 FOR LUW / DB2FORLUW / B10 - DB2 |
| Problem description: |
For 11.1 release only PowerPC platform is affected.
Regression could be noticed when one upgrades from 10.5 or
older.
On Linux, Db2 uses O_SYNC flag (04000000) to open
database containers, which enforces more strict file system
synchronisation requirements during writes than O_DSYNC
(00010000) flag used with releases 11.1 and older.
This might result in a performance degradation for workloads
that depend heavily on synchronous writes (e.g. on systems with
small bufferpools). The impact might vary for different file
systems and file system cache configuration for given
tablespace, with the system managed tablespaces (SMS) that use
file caching being affected the most.
For Db2's data consistency O_DSYNC is sufficient and this APAR
will address this regression.
Symptoms will include
- increased synchronous write time in Db2 monitoring interfaces
- Db2 threads blocked longer in the IO code path, waiting on
file system journal (e.g. as indicated by jbd2_log_wait_commit
WCHAN in "ps -T" output for Db2 engine/db2sysc). |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* N/A *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 v11.5.5.1 or request a special build *
**************************************************************** |
| Local Fix: |
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| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* N/A *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 v11.5.5.1 or request a special build *
**************************************************************** |
| Comment |
N/A |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 12.10.2021
12.10.2021
13.10.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
