标签：#board

HA dashboard cho Postgres replication: vì sao "có replica" không đồng nghĩa "đang HA", và cách để replica chết không âm thầm Streaming replication trong Postgres là một tunnel WAL từ primary sang standby: primary chạy một walsender cho mỗi standby, standby chạy một walreceiver nhận WAL và một startup process replay. Đau nhất trong vận hành không phải setup — mà là replica đã ngắt nhiều giờ mà không ai biết, tới lúc primary chết mới phát hiện HA thực ra là single-node từ tuần trước. HA dashboard là tập metric + alert được rút ra từ pg_stat_replication , pg_stat_wal_receiver , và pg_replication_slots để ép mọi trạng thái xấu — replica disconnect, replay đứng, slot pin WAL, sync standby biến mất — thành tín hiệu nhìn thấy được trước khi biến thành sự cố. Cơ chế hoạt động Trên primary, mỗi standby đang kết nối tạo ra một backend loại walsender — Postgres đọc WAL từ pg_wal/ (hoặc từ WAL buffers khi còn nóng) và stream qua replication connection. Trên standby, walreceiver nhận từng WAL record, ghi vào pg_wal/ local, fsync (tùy synchronous_commit ), rồi startup process apply record lên shared buffers — đây chính là replay. Bốn LSN xuất hiện trong luồng này và tương ứng với bốn cột trong pg_stat_replication : sent_lsn — byte cuối cùng primary đã gửi qua socket. write_lsn — byte cuối cùng standby đã write() vào OS page cache. flush_lsn — byte cuối cùng standby đã fsync xuống đĩa. replay_lsn — byte cuối cùng standby đã replay vào shared buffers (dữ liệu đã "thấy được" trên standby). Postgres docs quy định replay_lsn <= flush_lsn <= write_lsn <= sent_lsn <= pg_current_wal_lsn() — bốn "vạch" này chính là bốn nhịp của lag. Ba cột write_lag , flush_lag , replay_lag (kiểu interval ) là thời gian mà standby chậm hơn primary tương ứng với ba mốc write/flush/replay — được đo qua feedback message định kỳ từ standby. -- Trên primary: bức tranh đầy đủ cho một HA dashboard SELECT application_name , client_addr , state , -- streaming | catchup | startup | backup | stopping sync_state , --

I know a vocal group of people who swear by the number pad on their keyboard. And yet, for years I haven't cared about using one - until I put my hands on the Epomaker RT98. It's a mechanical keyboard with a charming retro aesthetic, a fun CRT-like screen, VIA compatibility, a nice typing feel, […]

The $149 Dune keyboard can be a meeting controller at least and a script-executing keypad at best.

ThingsBoard is one of the most capable open-source IoT platforms out there. But the first time you try to get a device publishing telemetry over MQTT, the documentation sends you in three different directions of device profiles, transport configurations, topic formats, and credential types. There are a lot of setups before you see a single data point on a dashboard. This post cuts through that. By the end, you will have a device sending live sensor data to ThingsBoard over MQTT and seeing it in the Latest Telemetry tab. No fluff, just working code. What You Need Before Starting A running ThingsBoard instance, Community Edition, is fine. You can use the live demo for a quick look, though a local Docker setup is more reliable for following along since the demo instance has usage limits. You also need mosquitto-clients installed for quick command-line testing and Python 3 with paho-mqtt for the scripting part. # Install mosquitto client tools sudo apt install mosquitto-clients # Install Python MQTT client pip install paho-mqtt Step 1: Create a Device and Grab the Access Token In the ThingsBoard UI, go to Entities → Devices and click the + button to add a new device. Name it something like sensor-01. Once created, click on the device and copy the access token from the credentials tab. This token is your MQTT username. No password needed. ThingsBoard uses it to identify which device is sending data. Step 2: Send Your First Telemetry via Command Line Before writing any code, test the connection with mosquitto_pub. This tells you immediately whether the setup works. mosquitto_pub -d -q 1 \ -h "YOUR_THINGSBOARD_HOST" \ -p 1883 \ -t "v1/devices/me/telemetry" \ -u "YOUR_ACCESS_TOKEN" \ -m '{"temperature": 25.4, "humidity": 62}' If you are running ThingsBoard 3.5 or later, you can use the shorter topic format: mosquitto_pub -d -q 1 \ -h "YOUR_THINGSBOARD_HOST" \ -p 1883 \ -t "v2/t" \ -u "YOUR_ACCESS_TOKEN" \ -m '{"temperature": 25.4, "humidity": 62}' Both do the same thing. v2

RAMageddon has come for computers. The price of memory chips, hard drives, and solid state storage has skyrocketed. That’s led to price increases on desktop and laptop RAM, SSDs, spinning hard drives, and pretty much everything that uses any of those things. Consoles are more expensive. Desktops are more expensive. Laptops are more expensive. Tablets […]

Looking for family fun this summer? You need these WIRED-recommended Prime Day board game deals.

Anime collaborations are everywhere, from Gundam watches and Naruto nights at Major League ballparks to just about anything Evangelion. But these Ghost in the Shell keyboards from Iqunix are some of the coolest examples I've seen of anime-inspired everyday tech. They look sick and they type and play great. At $249 they're a hefty upcharge […]

The Canadian pension giant will acquire an 8.2% stake in CtrlS, a tech giant that operates more than 15 data centers across India.

There is now a second free WSL management tool out there called WSL Dashboard , published by a developer who goes by owu on GitHub. It is open source, it has more GitHub stars than WSL UI, and it is clearly the product of real effort. I have no problem with any of that. Competition is good for users, and WSL deserves more than one good GUI. What I do have a problem with is this notice, which appears both on wslui.com and in the WSL Dashboard README: "This software is not distributed through the Microsoft Store. Any application listed there under the same name is unauthorized and may be counterfeit. Please do not download it to avoid potential scams." WSL UI is on the Microsoft Store. It has been since January. So that notice is, in plain terms, telling people that the genuine, certified, earlier WSL tool is a counterfeit scam. It isn't. And the entire claim falls apart the moment you look at the dates — all of which are public, timestamped, and independently verifiable. What this post is, and what it isn't This is not a "my project is better than yours" post. I'm not going to pick apart WSL Dashboard's features or pretend it's a bad piece of software. It isn't. This is a correction of one specific, factual claim: that the version of WSL UI on the Microsoft Store is unauthorized or counterfeit. That claim is demonstrably false, and because it's aimed at a tool people trust, it's worth setting straight properly — with evidence, not adjectives. The timeline Every date below comes from a public record. I've linked the sources so you don't have to take my word for any of it. Date Event How to verify 2008-12-11 octasoft.co.uk registered. Octasoft Ltd has existed for well over a decade. Nominet WHOIS for octasoft.co.uk 2025-12-14 The octasoft-ltd/wsl-ui repository is created. GitHub API ( created_at ) 2026-01-10 WSL UI's first public release, v0.2.0. WSL UI releases 2026-01-13 WSL UI v0.14.0 is published to the Microsoft Store. The announcement post 2026-01-18 The owu/wsl-

Most mechanical keyboards are great these days, with colorful looks and satisfying typing sounds - even in budget-friendly ranges. But every so often, one stops me dead in my tracks. In this case, two of them. I've been testing a pair of jaw-droppingly lovely keyboards that launched late last year. The Evoworks Evo75, a compact […]

While the AI fundraising machine keeps breaking its own records, some founders are building in the other direction. Mirror founder Brynn Putnam just raised money for Board, a startup focused on bringing people together through in-person games and social experiences. Cyberdeck creators are going viral crafting whimsical DIY computers that literally encourage users to touch grass. Unlike the AI-free browser crowd, this doesn’t just feel like backlash, […]

The Series F round values Coralogix at $1.6 billion and comes less than a year after its previous raise.