Disabling Transparent HugePages in RHEL7.x

Environment
[root@lab-12cr2 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.0 (Maipo)

Runtime Disable THP
Append below lines in /etc/rc.local
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
echo never > /sys/kernel/mm/transparent_hugepage/defrag
fi
Make sure that rc.local is running on reboot
chmod +x /etc/rc.d/rc.local
systemctl enable rc-local
systemctl status rc-local

Check the behavior on post reboot the operating system

[root@lab-12cr2 ~]# cat /sys/kernel/mm/transparent_hugepage/enabled
always madvise [never]
[root@lab-12cr2 ~]#
[root@lab-12cr2 ~]# cat /sys/kernel/mm/transparent_hugepage/defrag
always madvise [never]
[root@lab-12cr2 ~]#
[root@lab-12cr2 ~]# grep -i HugePages_Total /proc/meminfo
HugePages_Total: 0
[root@lab-12cr2 ~]# cat /proc/sys/vm/nr_hugepages
0
[root@lab-12cr2 ~]# grep -i AnonHugePages /proc/meminfo
AnonHugePages: 2048 kB

Permanent Disable THP
Oracle Linux 7 is similar, but uses GRUB2 so you need to edit the “/boot/grub2/grub.cfg” file using the grubby command.
[root@lab-12cr2 ~]# grubby –default-kernel
/boot/vmlinuz-3.10.0-123.el7.x86_64
[root@lab-12cr2 ~]# grubby –args=”transparent_hugepage=never” –update-kernel /boot/vmlinuz-3.10.0-123.el7.x86_64
[root@lab-12cr2 ~]# grubby –info /boot/vmlinuz-3.10.0-123.el7.x86_64
index=0
kernel=/boot/vmlinuz-3.10.0-123.el7.x86_64
args=”ro rd.lvm.lv=rhel/root crashkernel=auto rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet LANG=en_US.UTF-8 transparent_hugepage=never”
root=UUID=8190d97a-a2e9-44cd-9810-804def1d6f89
initrd=/boot/initramfs-3.10.0-123.el7.x86_64.img
title=Red Hat Enterprise Linux Server, with Linux 3.10.0-123.el7.x86_64
[root@lab-12cr2 ~]#

[root@lab-12cr2 ~]# grep -i “transparent_hugepage=never” /boot/grub2/grub.cfg
linux16 /vmlinuz-3.10.0-123.el7.x86_64 root=UUID=8190d97a-a2e9-44cd-9810-804def1d6f89 ro rd.lvm.lv=rhel/root crashkernel=auto rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet LANG=en_US.UTF-8 transparent_hugepage=never
[root@lab-12cr2 ~]# grep -i AnonHugePages /proc/meminfo
AnonHugePages: 0 kB
[root@lab-12cr2 ~]#
[root@lab-12cr2 ~]# grep -i HugePages_Total /proc/meminfo
HugePages_Total: 0
[root@lab-12cr2 ~]# cat /proc/sys/vm/nr_hugepages
0

Reference
Oracle MetaLink ALERT: Disable Transparent HugePages on SLES11, RHEL6, RHEL7, OL6, OL7 and UEK2 Kernels (Doc ID 1557478.1)

https://oracle-base.com/articles/linux/configuring-huge-pages-for-oracle-on-linux-64#disabling-transparent-hugepages

http://docs.oracle.com/database/122/LADBI/disabling-transparent-hugepages.htm#LADBI-GUID-02E9147D-D565-4AF8-B12A-8E6E9F74BEEA

Behavior Changes of RHEL 7.x Operating System

RHEL 7.x had taken lots of changes by default …

1.) Default file system changes: XFS
In RHEL7 /CentOS 7 and Oracle Linux have adopted XFS as their default file system.
Apart of these there are other numerous changes that you could find from faq forum like http://simplylinuxfaq.blogspot.in/p/major-difference-between-rhel-7-and-6.html

Some of them i found to be mandatory change before use it for Database Server in Production.
2.) Default HugePages is On On
Oracle recommends that you disable Transparent HugePages before you start installation.

3.) Default Setting RemoveIPC=yes
Setting RemoveIPC=yes on Redhat 7.2 Crashes ASM and Database Instances as Well as Any Application That Uses a Shared Memory Segment (SHM) or Semaphores (SEM)

Recommended to follow below steps
1. Set RemoveIPC=no in /etc/systemd/logind.conf
2. Reboot the server or restart systemd-logind as follows:
# systemctl daemon-reload
# systemctl restart systemd-logind

RHEL7: rc.local service not starting

Found this on some Red Hat blog:

“Systemd is a system and service manager for Linux operating systems. It is designed to be backwards compatible with SysV init scripts, and provides a number of features such as parallel startup of system services at boot time, on-demand activation of daemons, support for system state snapshots, or dependency-based service control logic. In Red Hat Enterprise Linux 7, systemd replaces Upstart as the default init system.”

chmod +x /etc/rc.d/rc.local
systemctl enable rc-local
systemctl status rc-local

https://grepora.com/2016/07/15/rhel7-rc-local-service-not-starting/

Remove Extra member from standby redo group

Tips , Reset below parameters before create standby redo group
db_create_online_log_dest_1=+DATA1 and db_create_online_log_dest_2=+DATA2

If you have set these parameters and you create standby redo log then it will be multiplexed in +DATA1 and +DATA2, Not recommended in Prod:)

@Primary
SQL> show parameter standby_file_management=MANUAL;
SQL> alter system set standby_file_management=MANUAL;

System altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_5.319.922465363’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_6.310.922465367’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_7.311.922465371’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_8.299.922465375’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_9.872.922465379’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_10.874.922465383’;

Database altered.

SQL> select member from v$logfile;

MEMBER
——————————————————————————–
+ORADATA/BLRDB/ONLINELOG/group_2.305.922465353
+ORADATA/BLRDB/ONLINELOG/group_2.622.922465353
+ORADATA/BLRDB/ONLINELOG/group_1.307.922465349
+ORADATA/BLRDB/ONLINELOG/group_1.306.922465351
+ORADATA/BLRDB/ONLINELOG/group_3.620.922465355
+ORADATA/BLRDB/ONLINELOG/group_3.323.922465357
+ORADATA/BLRDB/ONLINELOG/group_4.322.922465359
+ORADATA/BLRDB/ONLINELOG/group_4.320.922465361
+ORADATA/BLRDB/ONLINELOG/group_5.313.922465365
+ORADATA/BLRDB/ONLINELOG/group_6.301.922465369
+ORADATA/BLRDB/ONLINELOG/group_7.302.922465373

MEMBER
——————————————————————————–
+ORADATA/BLRDB/ONLINELOG/group_8.300.922465377
+ORADATA/BLRDB/ONLINELOG/group_9.873.922465381
+ORADATA/BLRDB/ONLINELOG/group_10.875.922465385
+ORADATA/BLRDB/ONLINELOG/group_11.1351.927649007

15 rows selected.

SQL> show parameter standby_file_management=AUTO scope=both;
SQL> ALTER SYSTEM SET standby_file_management=AUTO scope=both;

System altered.

SQL> select member from v$logfile;

MEMBER
——————————————————————————–
+ORADATA/BLRDB/ONLINELOG/group_2.305.922465353
+ORADATA/BLRDB/ONLINELOG/group_2.622.922465353
+ORADATA/BLRDB/ONLINELOG/group_1.307.922465349
+ORADATA/BLRDB/ONLINELOG/group_1.306.922465351
+ORADATA/BLRDB/ONLINELOG/group_3.620.922465355
+ORADATA/BLRDB/ONLINELOG/group_3.323.922465357
+ORADATA/BLRDB/ONLINELOG/group_4.322.922465359
+ORADATA/BLRDB/ONLINELOG/group_4.320.922465361
+ORADATA/BLRDB/ONLINELOG/group_5.313.922465365
+ORADATA/BLRDB/ONLINELOG/group_6.301.922465369
+ORADATA/BLRDB/ONLINELOG/group_7.302.922465373

MEMBER
——————————————————————————–
+ORADATA/BLRDB/ONLINELOG/group_8.300.922465377
+ORADATA/BLRDB/ONLINELOG/group_9.873.922465381
+ORADATA/BLRDB/ONLINELOG/group_10.875.922465385
+ORADATA/BLRDB/ONLINELOG/group_11.1351.927649007

15 rows selected.

SQL>
SQL> alter system switch logfile;

System altered.

SQL> exit
Disconnected from Oracle Database 12c Enterprise Edition Release 12.1

@DR

alter system set standby_file_management=MANUAL;
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_5.319.922465363’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_6.310.922465367’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_7.311.922465371’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_8.299.922465375’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_9.872.922465379’;

Database altered.

SQL> ALTER DATABASE DROP STANDBY LOGFILE MEMBER ‘+ORADATA/BLRDB/ONLINELOG/group_10.874.922465383′;

Database altered.

Standby redo logs without multiplexting:-

SQL> SELECT MEMBER FROM V$LOGFILE WHERE TYPE=’STANDBY’;

MEMBER
——————————————————————————–
+ORADATA/BLRDB/ONLINELOG/group_5.313.922465365
+ORADATA/BLRDB/ONLINELOG/group_6.301.922465369
+ORADATA/BLRDB/ONLINELOG/group_7.302.922465373
+ORADATA/BLRDB/ONLINELOG/group_8.300.922465377
+ORADATA/BLRDB/ONLINELOG/group_9.873.922465381
+ORADATA/BLRDB/ONLINELOG/group_10.875.922465385

SQL> SELECT GROUP#,THREAD#,STATUS FROM V$STANDBY_LOG;

GROUP# THREAD# STATUS
———- ———- ———-
5 1 UNASSIGNED
6 1 UNASSIGNED
7 1 UNASSIGNED
8 2 UNASSIGNED
9 2 UNASSIGNED
10 2 UNASSIGNED

Set PASSWORD UNLIMITED for PDB Application Schema

SQL> SELECT dba_users.USERNAME,
dba_users.ACCOUNT_STATUS,
dba_users.EXPIRY_DATE
FROM dba_users
WHERE ACCOUNT_STATUS=’OPEN’;
2 3 4 5
USERNAME ACCOUNT_STATUS EXPIRY_DA
——————————————————————————————————————————– ——————————– ———
NETVERTEXBLR OPE 17-APR-17
PDBADMIN OPE 17-MAR-17
ELITELDAPBLR OPE 21-MAR-17
ELITEPMRO OPE 13-APR-17
ELITEPROXYBLR OPE 17-APR-17
SYSTEM OPE 17-MAR-17
SYS OPE 17-MAR-17

7 rows selected.

SQL> ALTER PROFILE DEFAULT LIMIT PASSWORD_LIFE_TIME UNLIMITED;

Profile altered.

SQL> SELECT dba_users.USERNAME,
dba_users.ACCOUNT_STATUS,
dba_users.EXPIRY_DATE
FROM dba_users
WHERE ACCOUNT_STATUS=’OPEN’; 2 3 4 5

USERNAME ACCOUNT_STATUS EXPIRY_DA
——————————————————————————————————————————– ——————————– ———
NETVERTEXBLR OPEN
PDBADMIN OPEN
ELITELDAPBLR OPEN
ELITEPMRO OPEN
ELITEPROXYBLR OPEN
SYSTEM OPEN
SYS OPEN

7 rows selected.

SQL>

If you want to remove password expiry date for your schema then you have to use “ALTER PROFILE DEFAULT LIMIT PASSWORD_LIFE_TIME UNLIMITED;”

How to protect your cronjob in linux ?

https://en.wikipedia.org/wiki/Chattr

A very useful Linux tip on how to make files and directories undeletable even by the root user. You can apply this tip on all important configuration files so that no one accidentally or intentionally deletes it. To achieve this the chattr (Change Attribute) command is used it Linux. The chattr command “immunizes” the file not only from deletion but also modification. The chattr command does care about chmod values, even if a file has 777 permissions immunizing the file will prevent it from being deleted or modified.

chattr +i /path/to/filename

How to view file attributes ?
lsattr /path/to/directory

How to remove the immutable flag ?
chattr -i /path/to/file

http://websistent.com/make-undeletable-files-and-directories-linux/