How to reload all SCSI hosts and devices on Linux

After inserted a new SCSI disk, you may need to scan disks on the SCSI host. On the other side; you grow the current disk, you may need to re-scan disk to show new size. Most of cloud providers do this using cloud agents. But there may be some cases …

GRUB2 config make

If you change grub parameters (example /etc/default/grub), you need to make GRUB2 configurations in /boot.

grub2-mkconfig -o /boot/grub2/grub.cfg

If your grub installed with EFI, you may need some configurations. Example for CentOS:

grub2-mkconfig -o /boot/grub2/grub.cfg
grub2-mkconfig -o /boot/efi/EFI/centos/grub …

Advisory File locking with Go

File Locking is generally useful in an environment where multiple applications or processes may want to access(read/write) the same file. In such cases, it becomes important to protect integrity of file data and provide consistent view of data to all the processes.

This post studies only advisory file …

How to change root password of cloud image

There are ways to manipulate cloud images. I'm going to prefer libguestfs to change root password.

Install libguestfs and tools:

yum install guestfs-tools
yum install libguestfs libguestfs-appliance libguestfs-xfs

Change root password, mymagicpass is clean password, mydisk.img is primary disk image:

LIBGUESTFS_BACKEND=direct virt-customize --root-password password:mymagicpass -a mydisk.img …

How to enable serial console

We've been talking about cloud servers too much in recent years. How many of you remember the famous COM1, COM2 ports from old times? In this post, we are streaming console to serial ports again to access console from cloud providers.

On Linux

We just have to add this parameter …