Part 1 — Ext4 filesystem: data blocks, super blocks, inode structure Part 2 — Ext4 filesystem: extent, flex_bg, sparse_super Delayed Allocation The delayed allocation feature is enabled by default. That’s why the data may not be committed to the disk immediately when you try to write or modify a data block. I…

Part 1 — Ext4 filesystem: data blocks, super blocks, inode structure Part 3 — Ext4 file system: Delayed allocation, dirty data blocks You can examine your filesystem with dumpe2fs:

Part 2 — Ext4 filesystem: extent, flex_bg, sparse_super Part 3 — Ext4 file system: Delayed allocation, dirty data blocks ext4 was proposed to be added to Linux Kernel on 2006. It was added to Linux Kernel in 2008. Since then ext4 has become the default file system of many Linux…

TCP self-connect issue occurs when `src_ip:src_port == dst_ip:dst_port` You can try to access a local port to reproduce the self-connect issue. The application will likely connect to itself. This is my local port range: root@main:~# sysctl net.ipv4.ip_local_port_range net.ipv4.ip_local_port_range = 32768 60999 I randomly picked an even port number (why even…

You most probably know that TCP is reliable, and UDP is an unreliable protocol. Because TCP is a stream-oriented protocol. When a sender transmits some data to a receiver, the receiver will need to send an “acknowledge” to the sender. …

Google developed gVisor in 2018 and has been using it on Google Cloud for several years. gVisor is an application kernel that provides a secure environment for containers. Because it is OCI compatible, gVisor integrates with Kubernetes clusters and Docker containers. gVisor is a second layer that handles some syscalls…

When you need to create a mock object in Python, MagicMock comes in handy. However, there is a common issue that most people run into: Python returns MagicMock object instead of return_value Suppose your method calls another method, which in turn calls another method. MagicMock can be useful for such…

There is a tricky feature in PostgreSQL: Unlogged Table I’ll quote the description of the Unlogged Table from PostgreSQL.org: Data written to unlogged tables is not written to the write-ahead log, which makes them considerably faster than ordinary tables. However, they are not crash-safe: an unlogged table is automatically truncated…

If you are working on a large database and you want to improve the performance, then you will run into too many keywords. Let me type those keywords: Horizontal Scaling Vertical Scaling Horizontal Partitioning Vertical Partitioning Sharding I want to explain these keywords in simple sentences. Horizontal Scaling Adding new servers to…