Oracle, Linux, AWS, Azure, GCP
May 9, 2021 Leave a comment
I have used this command many times, but the interval between each usage is so big that I almost always forget the syntax.
So here it is:
# du -a / | sort -n -r | head -n 5 51190272 / 37705424 /root 33040524 /root/apache-tomcat-7.0.53 32802516 /root/apache-tomcat-7.0.53/logs 32802440 /root/apache-tomcat-7.0.53/logs/catalina.out
February 23, 2021 Leave a comment
Cluster nodes experienced high CPU usage, after investigation one of the top CPU consumers on the server has been found to be a TFA process (2nd place):
# Fri Feb 19 17:44:01 2021
AllCPU OneCPU PID User PR NI STime RSS Name
--------------------------------------------------------------------------------
11.75% 94.02% 23895 root 20 0 17:43 87M ora_m001_ORCL2
1.42% 11.39% 2468 root 20 0 Feb02 736M /opt/oracle.ahf/jre/bin/java -server -Xms256m -Xmx512m -Djava.awt.headless=true -Ddisable.checkForUpdate=true -XX:HeapDumpPath=/u01/app/oracle.ahf/data/rac02/diag/tfa -XX:ParallelGCThreads=5 oracle.rat.tfa.TFAMain /opt/oracle.ahf/tfaIn newer version of TFA, you can set CPU resource limit.
tfactl setresourcelimit
[-tool tool_name]
[-resource resource_type]
[-value value]To limit TFA to a maximum of 50% of a single CPU, run the following:
# tfactl setresourcelimit -value 0.5For more information, please check TFA official documentation.
If you don’t have newer version of TFA, you need to upgrade it first.
August 1, 2020 Leave a comment
There are several ways to identify that, I will suggest one of them using rpm -qf, that finds out what package a file belongs to:
Oracle Linux:
# rpm -qf /etc/redhat-release
oraclelinux-release-7.8-1.0.7.el7.x86_64
RHEL:
# rpm -qf /etc/redhat-release
redhat-release-server-7.8-2.el7.x86_64
August 26, 2019 Leave a comment
Problem:
One of our customer incorrectly changed fstab file and rebooted the OS. As a result, VM was not able to start. Fortunately, cloud where this VM was located supported serial console.
Solution:
We booted in single user mode through serial console and reverted the changes back. To boot in single user mode and update necessary file, do as follows:
Connect to the serial console and while OS is booting in a grub menu press e to edit the selected kernel:
Find line that starts with linux16 ( if you don’t see it press arrow down ), go to the end of this line and type rd.break.
Press ctrl+x.
Wait for a while and system will enter into single user mode:
During this time /sysroot is mounted in read only mode, you need to remount it in read write:
switch_root:/# mount -o remount,rw /sysroot switch_root:/# chroot /sysroot
You can revert any changes back by updating any file, in our case we updated fstab:
sh-4.2# vim /etc/fstab
You are a real hero, because you rescued your system!
April 16, 2019 Leave a comment
Problem:
1. Slow ssh connections
2. System seems slow when trying to su to another user
/var/log/secure contains the following errors:
pam_systemd(sshd:session): Failed to create session: Failed to activate
service 'org.freedesktop.login1': timed out
Solution:
1. Restart systemd-logind service
# systemctl restart systemd-logind
2. Restart server
# reboot
Note that the mentioned solutions are considered as temporary solutions (Frankly, I’ve never seen this error after restart. The problem happened with our two customers, who changed sshd_config file and did “something” after that, so the problem was caused by humman error in my all cases), for more information about this problem please see article at redhat site
https://access.redhat.com/discussions/3536621 .
November 27, 2018 1 Comment
Action:
I have deleted tigervnc rpm and was trying to reinstall it but got the following error:
yum install tigervnc*
https://rhui-3.microsoft.com...x86_64/dotnet/1/debug/repodata/repomd.xml: [Errno 14] curl#58 - "SSL peer rejected your certificate as expired."
Trying other mirror.
Actually, the problem is not related to tigervnc only, it is global. During this time I was not able to run yum update or any installation using yum.
Causes:
Red Hat Update Infrastructure (RHUI) certificate has expired and it needs to be updated.
Solution:
Update RHUI certificate using the following rpm:
For RHEL 7:
# curl -o azureclient.rpm https://rhui-1.microsoft.com/pulp/repos/microsoft-azure-rhel7/rhui-azure-rhel7-2.2-74.noarch.rpm
# sudo rpm -U azureclient.rpm
For RHEL 6:
# curl -o azureclient.rpm https://rhui-1.microsoft.com/pulp/repos/microsoft-azure-rhel6/rhui-azure-rhel6-2.2-74.noarch.rpm
# sudo rpm -U azureclient.rpm
August 9, 2018 Leave a comment
If you have downloaded Oracle 18c installation files, you may need to change downloaded file names from uppercase letters into lowercase. 🙂
[root@rac1 ~]# cd /sw
[root@rac1 sw]# for i in LINUX.X64_180000_*; do mv $i `echo $i |tr [:upper:] [:lower:]`; done
You may think these are just two files and why I need script? I can do it manually.. 🙂
You are right , but scripting is much more fun. Good luck!
September 11, 2017 Leave a comment
Assume we have timezone UTC:
[root@oradbfw-hq01-mgmt ~]# date
Mon Sep 11 09:29:27 UTC 2017
On many distributions , like OEL, CentOS.. . the timezone is conntrolled by localtime file located in /etc directory.
# cd /etc
Localtime is a symbolic link , so we can remove it
# rm localtime
All timezones are located under /usr/share/zoneinfo.
I live and my servers are located in Tbilisi, Georgia. So searching my timezone file:
[root@oradbfw-hq01-mgmt etc]# ll /usr/share/zoneinfo/Asia/Tbilisi
-rw-r–r–. 1 root root 1024 Mar 24 09:21 /usr/share/zoneinfo/Asia/Tbilisi
My country is not in Asia, but in Europe 🙂 this condition changed recently so Linux has not updated and still thinks we in Asia. (Don’t tell this to my goverment 🙂 )
Let’s create correct symbolic link:
# cd /etc
# ln -s /usr/share/zoneinfo/Asia/Tbilisi localtime
Let’s check that it was changed:
[root@oradbfw-hq01-mgmt etc]# date
Mon Sep 11 13:47:04 +04 2017
July 12, 2016 Leave a comment
0. Just to note –repoid parameter has two dashes in front (- – repoid). Unfortunately wordpress makes it one dash. Please, do not blame me 🙂
1. Create OEL.repo file in /etc/yum.repos.d and add the following entry
# vi /etc/yum.repos.d/OEL.repo
[oraclerpms]
name=OracleEnterpriseLinux
baseurl=http://yum.oracle.com/repo/OracleLinux/OL6/latest/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle
enabled=1
2. Install yum-utils and createrepo packages
# yum install yum-utils createrepo
3. It is better to add another disk and create repository there, do not use / disk(disk where OS is installed) for repository. It is just a best practice.
Create necessary folders:
# mkdir -p /OEL_repo/OEL6/latest
# mkdir -p /OEL_repo/logs
# mkdir -p /OEL_repo/scripts
4. Download rpms.
If you are using proxy you may need to set proxy parameters like  export http_proxy=http://proxy_server_ip:proxy_port/
/usr/bin/reposync –newest-only –repoid=oraclerpms -p /OEL_repo/OEL6/latest
5. After download completes create repository on downloaded rpms:
/usr/bin/createrepo /OEL_repo/OEL6/latest/oraclerpms/getPackage/
####################
The above steps should be done every time you want to update your local repository, so let’s create script and place all them in one file.
vi /OEL_repo/scripts/repo_sync.sh
#!/bin/bash
LOG_FILE=/OEL_repo/logs/repo_sync_$(date +%Y.%m.%d).log
# Delete old logs
find /OEL_repo/logs/repo_sync* -mtime +5 -delete; >> $LOG_FILE 2>&1#Clean cache
yum clean all# Sync repositories
/usr/bin/reposync /usr/bin/reposync –newest-only –repoid=oraclerpms -p /OEL_repo/OEL6/latest >> $LOG_FILE 2>&1/usr/bin/createrepo /OEL_repo/OEL6/latest/oraclerpms/getPackage/ >> $LOG_FILE 2>&1
2. Change permissions for the executable script:
# chmod u+x /OEL_repo/scripts/repo_sync.sh
3. Set up a CRON job to run the script on a daily basis. The following entry runs the script each day at 01:00.
0 1 * * * /OEL_repo/scripts/repo_sync.sh > /dev/null 2>&1
###############
1. Install the Apache HTTP servers, start it and make sure it restarts automatically on reboot.
# yum install httpd
# service httpd start
# chkconfig httpd on
2. Create directory and place link there
mkdir -p /var/www/html/OEL_repo/OEL6/latest
ln -s /OEL_repo/OEL6/latest/oraclerpms/getPackage/ /var/www/html/OEL_repo/OEL6/latest/x86_64# cd /var/www/html
# wget http://public-yum.oracle.com/RPM-GPG-KEY-oracle-ol6Note: /var/www/html is the default DocumentRoot directory. To check yours(sysadmin may have changed it) please check /etc/httpd/conf/httpd.conf file and find the keyword DocumentRoot
1. Configure clients
vi /etc/yum.repos.d/local-ol6.repo
[oraclerpms]
name=Oracle Linux $releasever Latest ($basearch)
baseurl=http://RepositoryServerHostname.domain.ge/OEL_repo/OEL6/latest/$basearch/
gpgkey=http://RepositoryServerHostname.domain.ge/RPM-GPG-KEY-oracle-ol6
gpgcheck=1
enabled=1
Now you are able to install packages on clients by
# yum install ntp
September 22, 2015 Leave a comment
unzip files:
unzip linuxamd64_12102_database_1of2.zip
unzip linuxamd64_12102_database_2of2.zip
mkdir -p /u01/app/oracle/product/12.1.0/dblb
chown -R oracle:oinstall /u01
chmod -R 775 /u01
oracle.install.option=INSTALL_DB_SWONLY
ORACLE_HOSTNAME=DBServerHostname
UNIX_GROUP_NAME=oinstall
INVENTORY_LOCATION=/u01/app/oraInventory
SELECTED_LANGUAGES=en
ORACLE_HOME=/u01/app/oracle/product/12.1.0/dblb
ORACLE_BASE=/u01/app/oracle
oracle.install.db.InstallEdition=EE
oracle.install.db.DBA_GROUP=dba
oracle.install.db.OPER_GROUP=dba
oracle.install.db.BACKUPDBA_GROUP=dba
oracle.install.db.DGDBA_GROUP=dba
oracle.install.db.KMDBA_GROUP=dba
SECURITY_UPDATES_VIA_MYORACLESUPPORT=false
DECLINE_SECURITY_UPDATES=true
./runInstaller -silent -responseFile /install/database/response/db_install.rsp  -waitforcompletion -showProgress
When it asks , connect to the server via root user and run
/u01/app/oracle/product/12.1.0/dblb/root.sh
You should also purge the recyclebin. For reducing upgrade time.
Note: these scripts should be run to the open database , that is turned on by 11g
export ORACLE_HOME=/u01/app/oracle/product/11.2.0/dblb
sqlplus / as sysdba @/u01/app/oracle/product/12.1.0/dblb/rdbms/admin/emremove.sql @/u01/app/oracle/product/12.1.0/dblb/rdbms/admin/olspreupgrade.sql purge recyclebin;
export ORACLE_HOME=/u01/app/oracle/product/11.2.0/dblb
/u01/app/oracle/product/12.1.0/dblb/bin/dbua -silent \ -sid ORCLÂ \ -oracleHome /u01/app/oracle/product/11.2.0/dblb \ -diagnosticDest /u01/app/oracle \ -recompile_invalid_objects true \ -degree_of_parallelism 40 \ -upgradeTimezone \ -emConfiguration NONE \ -keepHiddenParams \ -gatheringStatistics \ -upgrade_parallelism 40
cat /etc/oratab ORCL:/u01/app/oracle/product/12.1.0/dblb:N
cat /u01/app/oraInventory/ContentsXML/inventory.xml <VERSION_INFO> <SAVED_WITH>12.1.0.2.0</SAVED_WITH> <MINIMUM_VER>2.1.0.6.0</MINIMUM_VER> </VERSION_INFO>
Update the following parameters in your  .bash_profile:
export ORACLE_HOME=/u01/app/oracle/product/12.1.0/dblb
export LD_LIBRARY_PATH=/u01/app/oracle/product/12.1.0/dblb/lib
/u01/app/oracle/product/11.2.0/dblb/bin/lsnrctl stop
cp /u01/app/oracle/product/11.2.0/dblb/network/admin/listener.ora /u01/app/oracle/product/12.1.0/dblb/network/admin cp /u01/app/oracle/product/11.2.0/dblb/network/admin/tnsnames.ora /u01/app/oracle/product/12.1.0/dblb/network/admin
mv /u01/app/oracle/product/11.2.0/dblb/network/admin/tnsnames.ora /u01/app/oracle/product/11.2.0/dblb/network/admin/tnsnames.ora.old mv /u01/app/oracle/product/11.2.0/dblb/network/admin/listener.ora /u01/app/oracle/product/11.2.0/dblb/network/admin/listener.ora.old
/u01/app/oracle/product/12.1.0/dblb/bin/lsnrctl start
export ORACLE_HOME=/u01/app/oracle/product/12.1.0/dblb
sqlplus / as sysdba
select instance_name,version,status from v$instance;
/u01/app/oracle/product/11.2.0/dblb/deinstall/deinstall
