Author: MICHAL

Technology

Mirror Git repository

If you need to mirror remote repository and push it to another remote repo, then there is one thing you should do to be able to export all remote branches and not only the master. It will push all things remotely, but it varies from version to version so better double check.

Technology

Extending CentOS7 partition on Azure

Using CentOS7 templates on Azure could result in lack of LVM, swap and non auto-extendable partitions. Some other templates have such feature, but not all of them. In case you assigned bigger disk in Azure portal you need still to do few things. First delete /dev/sda2 partition: Then reboot to apply.

Technology

Zabbix Proxy 4.2 installation years later

Old Zabbix Proxy 4.2 installation could be quite confusing as you cannot grab the latest one to work with old Zabbix server. Fortunately there is archive packages repository at repo.zabbix.com/zabbix/4.2/ubuntu/pool/main/z/zabbix/. You need to keep track which operating systemu should be used. Refer to server requirements as it will be the same. So it’s Ubuntu 14, 16 or 18. First you should grab repository package which can be found named zabbix-release. For example: After installation with dpkg command, you can install particular proxy package with either MySQL, PostgreSQL or SQLite3. If you choose MySQL then you need to manually install database

Technology

Proxmox’s nesting setting with WordPress container

If you happen to use Proxmox’s LXC which stands for Linux Containers, then you might be interested in this one. Proxmox has this turnkey containers available to download from its UI. Among them there is WordPress. If you create a container using template then while creating remember to select nesting=on, because without this it will show permission denied on starting Apache2. Not quite familiar with nesting option but it is necessary to run this container.

Technology

Installing PostgreSQL 14 on CentOS 7

PostgreSQL 14 has few improvements over previous versions, especially older ones, like 9.6. This includes automatic data direction using partitioning. So, let’s install it on CentOS 7. Then you should login to the database and set password: Basic configuration includes firewall setup (if it’s active), access control and performance settings: I strongly recommend visiting pgtune.leopard.in.ua for tuning parameters. Last thing is to set interface address on which server will be listening, it’s set in: Now you are good to go.

Technology

Ohm’s law

Theory and practice [204] This is the SI unit of resistance. 1 ohm is the electrical resistance between two points on a conductor when a constant potential difference of one volt between the two points causes a current of one ampere in the conductor. Most, if not all, components have internal resistance, such as batteries. It is not a property that is easily measurable. Circuits intended to show some principles assume that, for example, the power source is an ideal cell and any internal resistances are compensated by additional components of such a circuit, assuming a certain margin of error.

Technology

Circuit simulation

Construction and testing of circuits in the TINA TI program To translate theory into practice, we can use the TINA package from DesignSoft for Texas Instruments. It is a tool for building virtual analog and digital circuits. The basic version provides the minimum necessary set of elements that can be arranged in the form of a circuit. However, the most important function (at least for me) is the ability to run simulations. All presented examples of simulations are prepared in TINA TI V9 (Schematic Editor), Special Complementary Basic Edition available free of charge. The schema sources are in the repository

Technology

Electric voltage

Measure of the strength of electric charges. Electrostatic potential difference. Electronics is based on physics. The basic concepts here are voltage, current and resistance. We should start with that. The voltage is therefore a measure of the strength of electric charges. The voltage between two points of an electric circuit or electric field is the difference in electrostatic potential between these points. We measure voltage in volts. We use a voltmeter to measure the voltage. We always measure voltage between two points because it is a potential difference. The voltage can be constant, variable, alternating. Why we use a given

Technology

Recovering Elasticsearch 7 after power outage

In case you encounted power outage or just blindly pressed restart button on your machine, there is high chance you will have some issues with your cluster. Mine has only one node, so there is no redundancy. If I lose indices then data is gone. Fortunately starting Elasticsearch and having red indicators not necessarily means data lose. I recently went that path. Log says that primary shards was missing. In such case you need to check if there are those indices listed: With that command look for red statuses. Internal mechanisms have this delay rule, so check every minute if