I remember someone asking me about changing the location of core file generated by postgres. We all know it creates under PGDATA by default, however some people want to avoid that as core file size will be huge some times and eats all space of data directory which will turn into shutdown of cluster. So I thought it will be good if we have an article which shows changing location.
On Linux servers, core file generation can be enabled by running "ulimit -c unlimited" before starting the server, or by using the -c option to pg_ctl start. On Windows, if you're running PostgreSQL 9.1, you can create a "crashdumps" subdirectory inside the data directory. On earlier versions, it's harder.
Before enabling/disabling, if you want to verify if your cluster started to generate core files or not, then check this. Ok, I have enabled core file gneration for my cluster, let change the location. Here are detailed steps:
-- Start the cluster using "-c" option(cluster user must be set to generate core files).
-- Check the core file pattern as root user using below command:
-- Change the kernel.core_pattern to the location in which you want to generate core files(Contact your Admin to do that). Please note that location given in kernel.core_pattern must be writable by the cluster user, or else the kernel will decline to write a core file there.
-- Verify if cluster is started to generate core file.
-- Check if cluster crash creates core files in the given location. Let me kill a process to do generate core.
-- Check the log entries
Wow, it generated in new location. Any comments/suggestions are most welcome.
On Linux servers, core file generation can be enabled by running "ulimit -c unlimited" before starting the server, or by using the -c option to pg_ctl start. On Windows, if you're running PostgreSQL 9.1, you can create a "crashdumps" subdirectory inside the data directory. On earlier versions, it's harder.
Before enabling/disabling, if you want to verify if your cluster started to generate core files or not, then check this. Ok, I have enabled core file gneration for my cluster, let change the location. Here are detailed steps:
-- Start the cluster using "-c" option(cluster user must be set to generate core files).
-- Check the core file pattern as root user using below command:
[root@localhost ~]# sysctl kernel.core_pattern kernel.core_pattern = |/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t e
-- Change the kernel.core_pattern to the location in which you want to generate core files(Contact your Admin to do that). Please note that location given in kernel.core_pattern must be writable by the cluster user, or else the kernel will decline to write a core file there.
[root@localhost ~]# echo "kernel.core_pattern=/tmp/core-%e-%s-%u-%g-%p-%t" >> /etc/sysctl.conf [root@localhost ~]# tail -5 /etc/sysctl.conf # max OS transmit buffer size in bytes net.core.wmem_max = 1048576 fs.file-max = 6815744 ######## kernel.core_pattern=/tmp/core-%e-%s-%u-%g-%p-%t [root@localhost ~]# [root@localhost ~]# [root@localhost ~]# sysctl -p |tail -5 net.core.rmem_max = 4194304 net.core.wmem_default = 262144 net.core.wmem_max = 1048576 fs.file-max = 6815744 kernel.core_pattern = /tmp/core-%e-%s-%u-%g-%p-%t [root@localhost ~]# %% - A single % character %p - PID of dumped process %u - real UID of dumped process %g - real GID of dumped process %s - number of signal causing dump %t - time of dump (seconds since 0:00h, 1 Jan 1970) %h - hostname (same as ’nodename’ returned by uname(2)) %e - executable filename
-- Verify if cluster is started to generate core file.
bash-4.1$ ps -ef|grep data|grep "9.3" 504 3405 1 0 20:44 ? 00:00:00 /opt/PostgresPlus/9.3AS/bin/edb-postgres -D /opt/PostgresPlus/9.3AS/data postgres 6155 1 0 21:37 pts/0 00:00:00 /opt/PostgreSQL/9.3/bin/postgres -D /opt/PostgreSQL/9.3/data bash-4.1$ grep -i core /proc/6155/limits Max core file size unlimited unlimited bytes bash-4.1$
-- Check if cluster crash creates core files in the given location. Let me kill a process to do generate core.
bash-4.1$ ps -ef|grep 6155 postgres 6155 1 0 21:37 pts/0 00:00:00 /opt/PostgreSQL/9.3/bin/postgres -D /opt/PostgreSQL/9.3/data postgres 6156 6155 0 21:37 ? 00:00:00 postgres: logger process postgres 6158 6155 0 21:37 ? 00:00:00 postgres: checkpointer process postgres 6159 6155 0 21:37 ? 00:00:00 postgres: writer process postgres 6160 6155 0 21:37 ? 00:00:00 postgres: wal writer process postgres 6161 6155 0 21:37 ? 00:00:00 postgres: autovacuum launcher process postgres 6162 6155 0 21:37 ? 00:00:00 postgres: stats collector process postgres 6527 6001 0 21:38 pts/0 00:00:00 grep 6155 bash-4.1$ kill -ABRT 6159 -- Killing writer process to get core dump. bash-4.1$ bash-4.1$ bash-4.1$ ls -ltrh /tmp/core*postgre* -rw-------. 1 postgres postgres 143M Feb 7 21:41 /tmp/core-postgres-6-501-501-6159-1423325468 bash-4.1$ bash-4.1$ date Sat Feb 7 21:41:25 IST 2015
-- Check the log entries
-bash-4.1$ grep "6159" postgresql-2015-02-07_213749.log 2015-02-07 21:41:09 IST LOG: background writer process (PID 6159) was terminated by signal 6: Aborted
Wow, it generated in new location. Any comments/suggestions are most welcome.
