Do not work for money. Working for knowledge, Money is a by-product.
Stop using the disk for anything. Then unmounted any file systems on the disk.
sudo umount ...
Deactivate any LVM groups.
sudo vgchange -an
Prevent disk damage with stop system using disk.
echo 1 | sudo tee /sys/block/{disk}/device/delete
Once you’ve done that, it should be safe to unplug SATA disk from running system.
echo 1 | sudo tee /sys/block/{disk}/device/rescan
BBR (Bottleneck Bandwidth and RTT) is a new congestion control algorithm which is contributed to the Linux kernel TCP stack by Google. With BBR in place, a Linux server can get significantly increased throughput and reduced latency for connections. Besides, it’s easy to deploy BBR because this algorithm requires only updates on the sender side, not in the network or on the receiver side.
Continue reading “Update CentOS kernel for deploy Google BBR”
Kernel sysctl configuration file for Linux
The following is suitable for dedicated web server, mail, file server etc.
place file in /etc/sysctl.d/60-zercle.conf
and run sysctl --system
When try to delete directory that contain a ton of files with rm -rf target_dir/ that very slow or even crashes, so we have other way to delete that directory with perl or rsync Continue reading “How to deleting large number of files in Linux”
Certbot’s DNS plugins which can be used to automate obtaining a wildcard certificate from Let’s Encrypt’s ACMEv2 server now are not available in some official repository.
IF you don’t want to wait, you can use these plugins now by use certbot from source.
Continue reading “Let’s Encrypt wildcard certificates with Certbot’s DNS plugins”
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software. Now we can run it from golang’s official docker ( https://hub.docker.com/_/golang/ ) with current terminal path.
Docker is a useful container but by default all docker’s stuff will place in /var/lib/docker in many case this will share with root disk space. For easy to maintain disk space we just change docker’s directory to separate disk or path. Continue reading “Install docker and change data directory”
dd command
# run as root dd if=/dev/source of=/dev/target bs=16M
pv command
# run as root apt-get install pv pv < /dev/source > /dev/target # or run with sudo sudo bash -c 'pv < /dev/source > /dev/target'
Edit /etc/modprobe.d/zfs.conf
# Set use max memory at half of system memory (ex. 4GB/2) options zfs zfs_arc_max=2147483648 # Increase scrub/resilver worker options zfs zfs_vdev_scrub_min_active=24 options zfs zfs_vdev_scrub_max_active=64 # Increase sync write options zfs zfs_vdev_sync_write_min_active=8 options zfs zfs_vdev_sync_write_max_active=32 # Increase sync reads options zfs zfs_vdev_sync_read_min_active=8 options zfs zfs_vdev_sync_read_max_active=32 # Increase async reads options zfs zfs_vdev_async_read_min_active=8 options zfs zfs_vdev_async_read_max_active=32 # Increase async write options zfs zfs_vdev_async_write_min_active=8 options zfs zfs_vdev_async_write_max_active=32
Save and reboot system to active configuration
Install lftp
#!/usr/bin/env bash apt update && apt -y full-upgrade apt -y install lftp exit 0
Mirror from remote to local
lftp http://mirror.remote.site/src-path -e "mirror -e -c -P=4 . /local/target-path; bye"
Explain
lftp remote_url/path -e [command]
mirror [option] source target
-e delete different files
-c continue transfer
-P=[number] number of parallel connections