In many environments, it's desirable to have the Oracle database and listener automatically shutdown and startup when the server reboots. If you have that requirement, then follow the next several steps to automate your database and listener shutdown and startup: Steps to configure auto startup/shutdown 1. Edit the /etc/oratab file, and place a Y at the end of the entry for the databases you want to automatically restart when the system reboots. You might need root privileges to edit the … [Read more...] about How to Automate Startup/Shutdown of Oracle Database and Listener on Linux
Linux
How to create xfs filesystem with 512 bytes block size
If you try to create a xfs filesystem with 512 bytes block size, you would get an error shown below: # mkfs.xfs -b size=512 [device] Minimum block size for CRC enabled file systems is 1024 bytes By default mkfs.xfs will enable CRC which forces a 1024 byte block. Turn off CRC to get 512 byte block. CRC enables enhanced error detection due to hardware issues, whilst the format changes also improve crash recovery algorithms and the ability of various tools to validate and repair metadata … [Read more...] about How to create xfs filesystem with 512 bytes block size
How to save command to history immediately after you type it in bash?
By default, if a user logs in a system via bash, all the command history will be saved after exit. How to save every command into ~/.bash_history immediately right after the user type it? How to save all commands typed in a session manually before exit bash? How to Log all Bash History Commands to syslog (/var/log/messages) in CentOS/RHEL How to change the number of commands stored in Bash History UNIX / Linux : Examples of bash history command to repeat last commands CentOS / RHEL : How … [Read more...] about How to save command to history immediately after you type it in bash?
How to Recreate a VDO (Virtual Data Optimizer) index
What is an VDO index VDO uses a high-performance deduplication index called UDS to detect duplicate blocks of data as they are being stored. There are 2 types of UDS indexes available, namely: Sparse UDS index - In general, Red Hat recommends using a sparse UDS index for all production use cases. This is an extremely efficient indexing data structure, requiring approximately one-tenth of a byte of DRAM per block in its deduplication window. Dense UDS index - The default configuration of the … [Read more...] about How to Recreate a VDO (Virtual Data Optimizer) index
How to Increase the Physical Size of a VDO (Virtual Data Optimizer) Volume
If a VDO volume does not have enough physical space, it will send I/O errors to the layers above. The fix for which is to add more physical space to VDO. The VDO physical size is the amount of physical storage VDO can be used to write metadata and user data. Growing the physical size of VDO is often done when planning for growth or if the volume has run out of physical space. VDO volumes are grown online while the volume is active and the operating mode is normal. The command to grow … [Read more...] about How to Increase the Physical Size of a VDO (Virtual Data Optimizer) Volume
How to Configure a Storage Device to Use VDO (Virtual Data Optimizer) Deduplication and Compression
Step 1 - Identify the device for VDO exampansion Identify the storage device that will be used for the VDO volume. Make sure that the storage device is not being used for another purpose. # lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 119.2G 0 disk ├─sda1 8:1 0 1G 0 part /boot └─sda2 8:2 0 118.2G 0 part ├─rhel-root 253:0 … [Read more...] about How to Configure a Storage Device to Use VDO (Virtual Data Optimizer) Deduplication and Compression
How to Resize (Increase) Logical Size of a VDO (Virtual Data Optimizer) volume in CentOS/RHEL
The logical size or thin-provisioned size of a VDO volume can be grown to a maximum of 4 petabytes. A common reason for doing this is to make more logical space available for file systems and applications. Make sure that if you are using a file system or volume manager above VDO that they are resized, as well. VDO volumes are grown online while the volume is running. The command to grow logically is: # vdo growLogical --name=[vdo volume name] --vdoLogicalSize=[size] Example 1. View the … [Read more...] about How to Resize (Increase) Logical Size of a VDO (Virtual Data Optimizer) volume in CentOS/RHEL
How to grant a user chown and chmod privileges on a specific directory in Linux
We want to give root privileges to a user. The user is allowed to run the chown and chmod commands on specific files or directories. How this can be allowed? Option #1 You can use group ownership and setgid directories. This allows everyone in the directory group to write to the [PATH] directory, and files created in that directory will be owned by the [PATH] group instead of the primary group of the user who created the file. # chgrp [GROUP] [PATH] # chmod g+ws [PATH] Option #2 1. … [Read more...] about How to grant a user chown and chmod privileges on a specific directory in Linux
How To Add/Remove Locale Archive in CentOS/RHEL 5,6
Occasionally the locale archive file(/usr/lib/locale/locale-archive) does not include a locale you want to use. In this case, you need to create a new locale file, or compile the locale from existent one by: # localedef -f [charmapfile] -i [inputfile] [outputpath] for example: # localedef -f SHIFT_JIS -i ja_JP ja_JP.SJIS The warning message "not ASCII compatible, locale not ISO C compliant" can be ignored. This command can provide appropriate locale even if you get the warning message … [Read more...] about How To Add/Remove Locale Archive in CentOS/RHEL 5,6
How to configure the logging of failed login attempts for vsftpd
Follow the steps outlined below to configure the logging of failed login attempts using pam. 1. Please add to pam_tally2 line after system-auth or password-auth line in /etc/pam.d/vsftpd file as below : auth include password-auth auth required pam_tally2.so deny=5 onerr=fail lock_time=600 serialize account required pam_tally2.so For example : # vi /etc/pam.d/vsftpd #%PAM-1.0 #%PAM-1.0 session optional pam_keyinit.so force revoke auth required pam_listfile.so item=user sense=deny … [Read more...] about How to configure the logging of failed login attempts for vsftpd