In most of the small and medium-sized enterprises (SMEs), we don’t have IT department and sometimes hire third-party for installation and setup. This post provides a checklist for things need to be aware while setting up Cisco Aironet 2800 access points.Continue reading “Cisco Aironet 2800 installation checklist”
Several days ago I noticed one of my backup to Amazon S3 was failed because the file is larger than 5GB and I didn’t use multipart upload. Code snippet as below. Works on AWS SDK for Ruby v3.Continue reading “Upload file larger than 5GB to Amazon S3 with Ruby”
Not every file system do data block checksumming. And the most popular one on Linux ecosystem – ext4 file system – is one of them. That means if there is a silent data corruption occur on the disk, it may not get noticed. The corrupted data may get backed up to the off-site storage device, and by time, the backup will get corrupted after it’s been replaced by up-to-date (corrupted) version. This is potentially dangerous if the data need to be stored for a long period of time.Continue reading “Data integrity – why I choose Btrfs (silent data corruption)”
While changing the password on Cisco Aironet 2800 controller over web-based management interface, it will update the password for the web interface and SSH login of the controller. However, it will not update the SSH login on every access points. This post provides a solution to change the SSH login for all the access points.
VLAN configuration is very different between HP and Cisco switches. HP is VLAN centred and Cisco is based on physical port. While managing Cisco switches, using a script to generate the config may ease the task. This post proposes a simple script to generate the config.
Only two lines
time timezone 600 time daylight-time-rule user-defined begin-date 10/01 end-date 04/01
Only two lines
clock timezone AEST 10 clock summer-time AEDT recurring 1 Sun Oct 2:00 1 Sun Apr 3:00
- Discount will replace double quote
“”and single and double quote
’. Where Markdown will keep the single and double quote as-is.
- To have a second level indentation on bullet points, Discount require two spaces, where Markdown only require one.
It is risky to issue a command like
sudo dd if=image of=/dev/sdb bs=1M due to the risk of typing
sdb to something else (e.g. internal drive). If an error has been made, the internal hard drive may get erased. This post proposes a solution by using udev rules, which will allow read/write access to USB drive without
sudo and no password required. These udev rules does not affect SATA-based storage devices.
ThinkPad X280 running Ubuntu 18.04 allows a brightness level from 0 to 1515. However, the Fn+F5/F6 hotkey only allows 21 levels of control. This post provides a solution and easy-to-use script for brightness control, best use with Guake.Continue reading “Precision brightness control on X280 running Ubuntu 18.04 (bionic)”
There is an issue that X280 may wake up while it’s connected to the ThinkPad USB-C hub. Here is the workaround for this issue.Continue reading “Prevent unwanted wake up for ThinkPad X280 running Ubuntu 18.04 (bionic)”
Before purchasing ThinkPad X280, I was concerned about the CPU throttling bug. It’s a bug which will throttle the CPU performance once it’s been triggered and will not restore the performance without a reboot.
I’ve developed a Ruby script for this test, and run it on X280 with i5-8250U processor. I did not reproduce the throttling issue that requires a reboot to restore the performance – whether the machine is powered by battery or connected to the power supply. However, I did discover a symptom which will under-clock the process to 123MHz under the certain load.
I’m an everyday Linux (Ubuntu) user moving from X201s to X280. This is my review after installing Ubuntu 18.04 (bionic) on X280.Continue reading “Review for ThinkPad X280 running Ubuntu 18.04 (bionic)”
I’ve followed the instructions from Bitnami for installing Let’s Encrypt certificate on Amazon Lightsail instance with Bitnami WordPress preloaded. The guide is very user-friendly and easy to follow. However, there is room for improvement in step 5 in certificate renewal.Continue reading “Improved Let’s Encrypt certificate renewal on Bitnami WordPress”