The Problem In some situations, a normal user within a Docker container cannot run 'su' command to switch user. When 'su' command is issued, the following error returns. $ su - Password: [entering correct password] su: Authentication failure The Solution The sticky permission may be missing in /usr/bin/su within the container. With root privilege, you may fix as follows: 1. First check the current permissions for the /usr/bin/su binary file. # ls -l /usr/bin/su -rwxr-xr-x 1 root … [Read more...] about “su: Authentication failure” – in Docker
How to Pause and Resume Docker Containers
Question: How to Pause and Resume running containers on docker host? This post will help to know about pausing and resuming any running containers on the Docker host. Let's first start the docker container "memory_test" on the docker host. # docker start memory_test memory_test To stop the pause the docker container: # docker pause memory_test memory_test Verify the state of docker container using "docker ps": # docker ps CONTAINER ID IMAGE COMMAND … [Read more...] about How to Pause and Resume Docker Containers
How to find docker storage device and its size (device mapper storage driver)
Question: How to find the running docker storage device when docker is using the device-mapper storage driver and then check the size of it? 1. Please run the "docker info" command to display docker system-wide information which contains the docker storage info. # docker info Containers: 0 Running: 0 Paused: 0 Stopped: 0 Images: 0 Server Version: 18.03.1-ol Storage Driver: devicemapper Pool Name: docker-251:0-102683530-pool Pool Blocksize: 65.54kB Base Device Size: … [Read more...] about How to find docker storage device and its size (device mapper storage driver)
Understanding “docker stats” Command Output
Question: How to monitor a running docker container performance metrics. For example, CPU,memory, I/O and network stats? The docker stats command can continuously report the basic CPU, memory, network and disk I/O metrics. For example: # docker stats a3f78cb32a8e CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS a3f78cb32a8e hello-world 0.00% 2.137MiB / 3.605GiB 0.06% 0B / 0B 9.95MB / 0B 0 Alternatively, you can … [Read more...] about Understanding “docker stats” Command Output
‘docker images’ command error – “Permission Denied”
The Problem A regular user is not able list images using docker images command. Following error can be observed. user01> docker images Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.27/images/json: dial unix /var/run/docker.sock: connect: permission denied The Solution User is not part of docker group and doesn't have permissions to execute docker related commands. Add regular user to … [Read more...] about ‘docker images’ command error – “Permission Denied”
Docker Basics – Expose ports, port binding and docker link
This post illustrates three methods to link Docker containers. Expose ports and port binding Expose ports This method is used for within the same network or the docker host. Containers on the same network can talk to each other over their exposed ports and you can expose the ports by one of the below methods. - Put EXPOSE 80 (or any port you want) in your Dockerfile that’s going to tell Docker that your container’s service can be connected to on port 80. - Expose a port using '--expose … [Read more...] about Docker Basics – Expose ports, port binding and docker link
How to split BCV and open oracle ASM database
BCV (Business Continuance Volume ) is the target volume for EMC Symmetrix TimeFinder/Mirror process. When a BCV is fully synchronized with a data device, the BCV is separated or split, thus becomes available to a host for backup or other host processes. In short, a BCV split is a device to be a clone of another device. Before you use BCV split as oracle backup, you need to narrow down what is contained on the backed up volumes. You can use BCV split to backup only asm disks together with rdbms … [Read more...] about How to split BCV and open oracle ASM database
How to change the interface name in CentOS/RHEL 8 using prefixdevname
This post will help to change the network interface name using prefixdevname utility in CentOS/RHEL 8 systems. Installation and configuration 1. Install the required package using dnf utility: # dnf install prefixdevname 2. Append the net.ifnames.prefix=[ABCD] using grubby command: (ABCD to replaced with own prefix, eg: net). # grubby --update-kernel=$(grubby --default-kernel) --args="net.ifnames.prefix=net" 3. Reboot the system to take effect: # reboot 4. After system rebooted, … [Read more...] about How to change the interface name in CentOS/RHEL 8 using prefixdevname
Beginners Guide to Implementing Table Maintenance in MySQL
Table maintenance operations are useful for identifying and correcting database problems such as the following: – Tables that become damaged as a result of a server crash. – Slow query processing on tables. Many tools are available for performing table maintenance: MySQL Workbench MySQL Enterprise Monitor SQL (DML) maintenance statements Utilities: mysqlcheck and myisamchk Server auto-recovery SQL for Table Maintenance Operations There are multiple SQL statements for performing … [Read more...] about Beginners Guide to Implementing Table Maintenance in MySQL
MySQL – How to Set Maximum Rates for Connections and Queries
There are several options to implement firewall like features for a MySQL instance. Some of these are described below. When an account is mentioned it refers to the combination of a username connected from a given host, i.e. username@hostname. MySQL Enterprise Firewall MySQL Enterprise Firewall will allow you to create a whitelist per account specifying the normalized queries that the account are allowed to execute. It is available in the Enterprise Edition of MySQL Server in versions … [Read more...] about MySQL – How to Set Maximum Rates for Connections and Queries