What is SELinux Context When SELinux is enforced in the system, it checks for rules on which process can access which files, directories, and ports. Every file, process, directory, and the port has a special security label known as an SELinux context, which is a name used to determine whether a process can access a file, directory, or port. By default, the policy does not allow any interaction unless an explicit rule grants access. SELinux labels have different contexts: user, role, type, … [Read more...] about How to List and Set SELinux Context for MySQL Server
How to Modify Static Parameter value in spfile
If you try changing a static parameter value in the SPFILE used at instance startup, you would get the following error message: SQL> alter system set audit_trail=DB scope=both; * ERROR at line 1: ORA-02095: specified initialization parameter cannot be modified SCOPE=BOTH applies the modification at the instance level and in the spfile used at startup. Use the value that applies the modification in the spfile only, provided that the spfile was used at … [Read more...] about How to Modify Static Parameter value in spfile
Troubleshooting slow network communication or Connection Timeouts in Linux
Troubleshooting a slow network or network packet drops can be tricky. In addition to slower network communication, there may be additional symptoms observed, such as : Attempts to connect to a server with ssh and/or sftp results in time-outs or a delayed response. When the network load goes high, there are high number of network retransmits observed. There may be large number of packet drops seen in the output of " ifconfig eth[x] " command. Some other symptoms also include: - The … [Read more...] about Troubleshooting slow network communication or Connection Timeouts in Linux
Unable to instantiate disk “ASM_DISK” – error on running ‘oracleasm scandisks’ command
The Problem The new disk has been assigned to a host and the user needs to run a scandisk. But the command fails to instantiate new disks with the below error. # oracleasm scandisks Reloading disk partitions: done Cleaning any stale ASM disks... Scanning system for ASM disks... Instantiating disk "ASM_DISK_01" Unable to instantiate disk "ASM_DISK_01" Instantiating disk "ASM_DISK_02" Unable to instantiate disk "ASM_DISK_02" Instantiating disk "ASM_DISK_03" Unable to instantiate disk … [Read more...] about Unable to instantiate disk “ASM_DISK” – error on running ‘oracleasm scandisks’ command
CentOS/RHEL – vgs command reports error: “global/global_filter” unknown
The Problem The user has set a new value for the parameter global_filter in the /etc/lvm/lvm.conf file. After setting the parameter value 'vgs' command gives below error: # vgs Configuration setting "global/global_filter" unknown. ... The Solution User has put the "global_filter" parameter under the 'global {}' section in /etc/lvm/lvm.conf configuration file. global { ... global_filter = [ "r/.*/" ] ... } Perform the following steps to solve the LVM filter issue: 1. Take … [Read more...] about CentOS/RHEL – vgs command reports error: “global/global_filter” unknown
3 Ways of Increasing Swap Space on Linux
Sometimes the default physical memory is not enough to serve certain tasks or processes. It may happen that the processes are swapping more memory in and out of the swap space. This post helps to explain how to increase the swap memory on a Linux system. There will be 3 different ways explained in this post, it depends on the availability of each case to use any of these options. Method #1 : Use a new disk 1. Add a new disk to the Linux instance from the available storage. 2. Once the … [Read more...] about 3 Ways of Increasing Swap Space on Linux
How to resize (extend) a partition-based file system in Linux
Note: Resizing a filesystem on a disk parition can be dangerous and can result in loss of data. Make sure you have the backup taken prior to following the steps outlined below. Caveats 1. The filesystem you want to resize must reside on the last partition of the disk. There is no data loss in this case as we recreate the partition without destroying the actual data on it. 2. In case it is not the last partition, you have to destroy the data and recreate a new partition with the desired … [Read more...] about How to resize (extend) a partition-based file system in Linux
Basic “chmod” Command examples in Linux
The Linux command to change permissions on a file or directory is chmod, which we like to read as change file mode. chmod has two operating modes: symbolic mode numeric/octal mode To change permission using the Linux chmod command we have to follow some syntax and rules. As we discussed above we can change permission using Numerical and Alphabetical way, here I have explained both methods with all tricks. Alphabetical Way To use this method you have to remember below rules and … [Read more...] about Basic “chmod” Command examples in Linux
“lsb_release: command not found” – Fix in CentOS/RHEL
The Problem While executing the command "lsb_release -r" to display the release number of the currently installed distribution, user gets below error: # lsb_release -v -bash: lsb_release: command not found How this can be resolved? The Solution To check the RedHat/CentOS version one can use the “lsb_release” command. In most cases, the package providing this command is not installed by default on the systems. To check which package provides the lsb_release command use the below … [Read more...] about “lsb_release: command not found” – Fix in CentOS/RHEL
How to enable the automatic extension for a thin LVM volume
By default, the automatic extension is set to '100' # grep thin_pool_autoextend_threshold /etc/lvm/lvm.conf # Configuration option activation/thin_pool_autoextend_threshold. # thin_pool_autoextend_threshold = 70 thin_pool_autoextend_threshold = 100 These settings imply the function has been disabled. From the /etc/lvm/lvm.conf configuration file: # 'thin_pool_autoextend_threshold' and 'thin_pool_autoextend_percent' define # how to handle automatic pool extension. The former defines … [Read more...] about How to enable the automatic extension for a thin LVM volume