Informix - Problem description
Problem IT08621 | Status: Closed |
READAHEAD THREAD CAN RUN CONTINOUSLY BLOCKING A CPU VP HEREBY AND RESULTING IN HANG OF THE INSTANCE | |
product: | |
INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10 | |
Problem description: | |
This has been observed during a migration from 11.70 to 12.10 with an instance that has about 3700 compressed tables. During the migration to 12.10 an attached index on the compression dictionary partition is created. The instance message log is showing: 14:34:48 *** FromVersion=18 ToVersion=25 entity_ver=26 targetVersion=28 indexVersion=5 *** 14:34:48 *** FromVersion=25 ToVersion=26 entity_ver=26 targetVersion=28 indexVersion=6 *** 14:34:48 *** FromVersion=26 ToVersion=27 entity_ver=26 targetVersion=28 indexVersion=7 *** 14:34:48 *** RSAM 1 12.10.xC1 *** The convert thread is in the state ready while the readahead thread is continuously running on the CPU VP. There is only one CPU VP configured. The stack of the convert thread is showing: ... kyadd rsaddindex rsam_1210_convert do_each_version_work generic_fw_main convertSM th_init_initgls startup So you are seeing in an onstat -g ath: 19 45b765f0 0 3 ready 1cpu* kaio 24 45e19028 44c2a928 3 running 1cpu readahead_0 21 45c5d808 44c28ee8 3 IO Wait 1cpu convert and onstat -g glo shows that the CPU time used is increasing for CPU VP 1. | |
Problem Summary: | |
**************************************************************** * USERS AFFECTED: * * users migrating to 12.10 on a single CPU system with a * * significant number of compressed tables * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Update to IBM Informix Server 12.10.xC6 * **************************************************************** | |
Local Fix: | |
As a temporary relief you can attempt the migration again. - Stop current instance "kill -9 on PID of CPU VP 1". - Use onrestorept to revert to previous instance state before the migration or use a backup. - Change onconfig parameter AUTO_READAHEAD to 0 and VPCLASS to use more than one CPU VP. - Disable KAIO (on Linux for example set environment variable KAIOOFF before instance startup). - Start migration again with oninit -v. | |
Solution | |
Problem Fixed In IBM Informix Server 12.10.xC6 | |
Workaround | |
not known / see Local fix | |
Timestamps | |
Date - problem reported : Date - problem closed : Date - last modified : | 29.04.2015 30.12.2015 30.12.2015 |
Problem solved at the following versions (IBM BugInfos) | |
12.10.xC6 | |
Problem solved according to the fixlist(s) of the following version(s) | |
12.10.xC6 |