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5 этап - Automating Oracle database Shutdown and Startup by systemd

Huge Pages on Oracle Linux

Quick checking
# cat /proc/sys/vm/nr_hugepages
2054

or

# cat /proc/meminfo | grep Huge
AnonHugePages:         0 kB
HugePages_Total:    2054
HugePages_Free:      546
HugePages_Rsvd:      542
HugePages_Surp:        0
Hugepagesize:       2048 kB

Checking if transparent huge pages are disabled

# cat /sys/kernel/mm/transparent_hugepage/enabled`  
always madvise [never]`  
Viewing database 12.1 alert log  
**********************************************************************
Dump of system resources acquired for SHARED GLOBAL AREA (SGA)
Per process system memlock (soft) limit = 128G
Expected per process system memlock (soft) limit to lock
SHARED GLOBAL AREA (SGA) into memory: 2050M
Available system pagesizes:
4K, 2048K``Mon Oct 16 12:28:54 2017
Supported system pagesize(s):
PAGESIZE  AVAILABLE_PAGES  EXPECTED_PAGES  ALLOCATED_PAGES  ERROR(s)
   4K       Configured               3               3        NONE
2048K             2054            1025            1025        NONE
**********************************************************************

Viewing database 11.2 alert log

************************ Large Pages Information *******************
Per process system memlock (soft) limit = 128 GB
Total Shared Global Region in Large Pages = 2050 MB (100%)
Large Pages used by this instance: 1025 (2050 MB)
Large Pages unused system wide = 4 (8192 KB)
Large Pages configured system wide = 2054 (4108 MB)
Large Page size = 2048 KB
********************************************************************
If number of Huge pages is less than required, than SGA will use both page types. Database 12.1 aler.log:
  PAGESIZE  AVAILABLE_PAGES  EXPECTED_PAGES  ALLOCATED_PAGES  ERROR(s)``        4K       Configured               3       187704        NONE``     2048K              659            1025             658        NONE
Simplified setup
  1. Have the memlock user limit set in /etc/security/limits.conf file. Set the value (in KB) slightly smaller than total RAM (90%) , at least it must be bigger than HugePages size. *   soft   memlock    14680064 *   hard   memlock    14680064 Atentu! If you use systemd to auto startup databases, systemd ignores limits.conf. You need to add the following to a service unit file
[Service]
LimitMEMLOCK=infinity
LimitNOFILE=65535
  1. Get the required number of pages from alert.log (EXPECTED_PAGES) or by running Oracle script hugepages_settings.sh (Doc ID 401749.1)
  2. edit vm.nr_hugepages in /etc/sysctl.conf as root
  3. to reload the parameters, reboot Linux or use sysctl -p Proper setup and more info
HugePages on Oracle Linux 64-bit (Doc ID 361468.1)
HugePages on Linux: What It Is... and What It Is Not... (Doc ID 361323.1)
Oracle Linux: Shell Script to Calculate Values Recommended Linux HugePages / HugeTLB Configuration (Doc ID 401749.1)
Automating by systemd

alternatives are Oracle Restart or SysV init ( /etc/init.d in older Linux).
Service Unit file typically has extension .service and stored in
/usr/lib/systemd/system
/etc/systemd/system
/usr/lib/systemd/user
/etc/systemd/user

Create or edit a service unit file:

cd /etc/systemd/system  
vi oracle\_database.service  
\[Unit\]  
Description=The Oracle Database Service  
After=network.target  
  
\[Service\]  
Type=forking  
RemainAfterExit=yes  
KillMode=none  
TimeoutStopSec=10min  
\# memlock limit is needed for SGA to use HugePages  
LimitMEMLOCK=infinity  
LimitNOFILE=65535  
  
User=oracle  
Group=oinstall  
\# Please use absolute path here  
\# ExecStart=$ORACLE\_HOME/bin/dbstart $ORACLE\_HOME &  
\# First argument of dbstart is used to bring up Listener  
ExecStart=/opt/oracle/product/12.1.0/se2\_1/bin/dbstart /opt/oracle/product/12.1.0/se2\_1 &  
ExecStop=/opt/oracle/product/12.1.0/se2\_1/bin/dbshut /opt/oracle/product/12.1.0/se2\_1  
Restart=no  
  
\[Install\]  
\# Puts wants directive for the other units in the relationship  
  
WantedBy=default.target
First argument of dbstart/dbshut is used to bring up/shutdown Oracle Listener. This script will start all databases listed in the /etc/oratab file whose third field is a "Y". If you use ASM or cluster services, read more in dbstart description.

Источник: https://alexzy.blogspot.com/2017/10/

Huge Pages
systemd ignores /etc/security/limits.conf. If HugePages are configured, you need to use LimitMEMLOCK and LimitNOFILE, otherwise SGA will use small pages and database alert log will show:

Increase per process memlock (soft) limit to at least 2050MB to lock 100% of SHARED GLOBAL AREA (SGA) pages into physical memory
**TimeoutStopSec**= Configures the time to wait for stop. If a service is asked to stop, but does not terminate in the specified time, it will be terminated forcibly via SIGTERM, and after another timeout of equal duration with SIGKILL (see KillMode= in systemd.kill(5)). Takes a unit-less value in seconds, or a time span value such as "5min 20s". Pass "infinity" to disable the timeout logic. Defaults to DefaultTimeoutStopSec= from the manager configuration file (see systemd-system.conf(5)). For more info use man systemd.service

reload systemd and enable the service:
systemctl daemon-reload
systemctl enable oracle_database.service
list services:
systemctl list-unit-files --type service|grep oracle
Start the service and check its status
systemctl start oracle_database.service
systemctl status oracle_database.service

Источник: Huge Pages on Oracle Linux

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