Turn single disk ZFS to mirrored ZFS

 I wanted to add some redundancy by mirroring disk. So I did it. Notice "-s" in zpool attach command so resilvering is done sequentially.

Fix ZFS device names

So you screwed up and created zpool using /dev/sdb instead of /dev/disk/by-id/ata-* as a device? Then you tried to fix it and ended up with cryptic wwn- as device name. Here's dirty solution. Make sure to run those commands right after each other. Otherwise it will get imported back with wrong device names automatically -- before you have time to do it with correct names.

Repairing beeping Lenovo T440p

Laptop powers on but nothing on screen. This is often because eeprom (Winbond W25Q32FVSIQ, 32Mbit / 4MB, 2.7V - 3.6V, SPI/QPI) loses programming over time and one day laptop will simply no longer boot. At first it will blink some leds on keyboard and turns off. Then it will degrade to just beeping on boot.

Hiding Azure Enterprise App from users using az cli or PowerShell

Toggling "Visible to users" setting on portal adds / removes tag called HideApp.

How to get list of Azure service tags and IP ranges using az cli

Microsoft provides weekly updated list of IP addresses used by various Azure features as downloadable JSON file on their webpage. Automating download of it is however not supported and prone to breakage. Same information is now also available via Azure Service Tag Discovery API. New API is still in public preview state and list of IPs it provides is far less than downloadble file contains. So either list of IPs from API is tailored for your particular subscription or it is incomplete. Discovery API requires authenticated session to Azure so we need to create service principal and custom RBAC role to keep things secure. See you for more after the break.

RHEL7 / CentOS7 network interface going down once per hour

There's really bizarre bug in RHEL7 / CentOS7. Once per hour NetworkManager will remove IP addresses from ethernet interface after hitting some bug and triggering "link loss" action. Interface may come back by itself or may not. It does come back when you login as root on console as login triggers some repair action part via systemd...

Migrating user accounts from older Linux to RHEL7 / CentOS7

Another pointless change just to break backwards compatibility - RHEL7 and CentOS7 prevent users with uid lower than 1000 from logging in. This is bad when you're migrating accounts from existing Linux server where uids start at 500.