Linux: To create an ext4 file system on Linux using LVM (Logical Volume Manager), follow these steps:

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To create an ext4 file system on Linux using LVM (Logical Volume Manager), follow these steps:

  1. Install LVM Tools (if not already installed): Ensure that the LVM tools are installed on your system. You can install them using your package manager. On Debian/Ubuntu, you can use apt, and on Red Hat/CentOS, you can use yum:
    • For Debian/Ubuntu
      • sudo apt-get install lvm2
    • For Red Hat/CentOS
      • sudo yum install lvm2
  2. Create Physical Volumes (PVs): Start by creating one or more physical volumes on your available storage devices, such as hard drives or partitions. Replace /dev/sdX with the appropriate device names:bash
    • sudo pvcreate /dev/sdX
  3. Create a Volume Group (VG): After creating one or more physical volumes, you can create a volume group that combines these physical volumes into a single pool of storage. Replace myvg with your desired volume group name:bash
    • sudo vgcreate myvg /dev/sdX1 /dev/sdX2 # Use the appropriate device names
  4. Create Logical Volumes (LVs): Now, create one or more logical volumes within the volume group. Specify the size and name for each logical volume. Replace /dev/myvg/mylv with your desired logical volume name and size:bash
    • sudo lvcreate -n mylv -L 10G myvg # Replace 10G with your desired size
  5. Create the ext4 File System: You can create the ext4 file system on the logical volume you just created using the mkfs.ext4 command:bash
    • sudo mkfs.ext4 /dev/myvg/mylv
  6. Mount the ext4 File System: Create a mount point where you want to access the ext4 file system and then mount it:bash
    • sudo mkdir /mnt/myext4 sudo mount /dev/myvg/mylv /mnt/myext4
  7. Add Entry to /etc/fstab (Optional): To make the mount persistent across reboots, add an entry to the /etc/fstab file:bash
    • echo "/dev/myvg/mylv /mnt/myext4 ext4 defaults 0 2" | sudo tee -a /etc/fstab Replace /dev/myvg/mylv and /mnt/myext4 with your logical volume and mount point.
  8. Verify and Use: You can now verify that the ext4 file system is mounted correctly and start using it:bash
    • df -h This command will show you the available disk space on the mounted ext4 file system.

That’s it! You’ve created an ext4 file system on a logical volume managed by LVM. You can adjust the sizes and names to fit your specific requirements.

Linux boot troubleshooting

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Troubleshooting a Linux system that does not boot can be a complex process, and the steps you take will depend on the specific symptoms and hardware involved. Here’s a general guide to help you diagnose and potentially fix the issue:

  1. Check Hardware Connections:
    • Ensure that all cables and hardware components (such as RAM, hard drive, power cables) are properly connected.
  2. Check BIOS/UEFI Settings:
    • Access your system’s BIOS/UEFI settings and make sure the boot order is configured correctly, with the system drive as the first boot option.
  3. Boot into Recovery Mode or GRUB:
    • If your system uses GRUB (the boot loader for Linux), try to access the GRUB menu during boot by pressing the appropriate key (usually Esc, Shift, or F2) and boot into recovery mode if available.
  4. Check for Error Messages:
    • Pay attention to any error messages or warnings that appear on the screen during boot. These messages can provide valuable clues about the issue.
  5. Run Hardware Diagnostics:
    • If you suspect a hardware problem, run hardware diagnostics tools if available. Most manufacturers provide these tools, and they can help identify faulty components.
  6. Check for Disk Errors:
    • Use a live Linux distribution (on a USB or CD/DVD) to boot into a live environment. Then, check your system’s hard drive for errors and repair any filesystem issues. You can use commands like fsck or GUI-based tools.
  7. Inspect Grub Configuration:
    • If the issue seems related to GRUB, check its configuration files (usually in /etc/default/grub and /etc/grub.d/) for errors or misconfigurations. You might need to regenerate the GRUB configuration using update-grub.
  8. Examine Kernel Parameters:
    • In GRUB, you can edit kernel parameters to disable graphical boot and enable verbose output. This can help you see where the boot process is failing. Look for kernel panic messages.
  9. Check for Disk Space Issues:
    • Insufficient disk space can sometimes prevent a system from booting. Use a live environment to check the available disk space on your system’s partitions.
  10. Repair Bootloader:
    • If the bootloader is corrupted, you might need to repair it. The method for repairing GRUB or other bootloaders may vary depending on your Linux distribution. Use the appropriate commands or tools to reinstall or repair the bootloader.
  11. Check for Kernel Issues:
    • If the boot process is failing at the kernel stage, you may need to boot into a previous kernel version (if available) or reinstall/update the kernel.
  12. Backup and Restore:
    • If all else fails, consider backing up your important data using a live environment and then reinstalling the Linux distribution.
  13. Logs:
    • Check system logs, such as /var/log/syslog or /var/log/boot.log, for any clues about what’s causing the boot failure.
  14. Seek Help Online:
    • If you’re still unable to resolve the issue, consider seeking help on Linux forums or communities. Provide as much detail as possible about the problem and the error messages you’ve encountered.

Remember that diagnosing and troubleshooting boot issues can be complex, and it’s important to be cautious when making changes to your system. Be sure to back up your data before attempting any major fixes, and if you’re unsure about a particular step, seek assistance from experienced users or professionals.

Linux Foundation Collaboration Summit 2014

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Long time since I wanted to start this new blog, in the last five years I have experienced a few professional transitions, changing employer, from a Software Engineering role to System Administrator role, from developing and/or testing software for “Legacy” operating system and proprietary software to infrastructure Services Delivery using large scale UNIX and Linux customer’s environments. In the past trying to imagine what challenges Systems Administrators have to develop systems management software to actually know it from the first hand. Now in the last year got a new job role working on process, procedures and tools improvements and knowledge management activities for UNIX and Linux Infrastructure Delivery.

Some of my stronger skills are on operating systems running on Power Systems (AIX and IBM i). Since 2006 until 2013 I have participated as speaker and attendee on Power Systems technical conferences sharing experiences using “i” and AIX operating systems with Power Systems Community.

However we can see how business have been migrating workloads from “Legacy” operating systems to Linux successfully. For that reason one objectives for this year was to attend to a Linux community conference to get deeper skills on Linux. Late February I got an invitation from Linux Foundation staff to attend to Collaboration Summit 2014 that was an exclusive invitation-only event in Napa, CA, so I decided to take the opportunity to attend to tree day summit and also attend to an one day KVM workshop.

Knowing that open source linux virtualization technologies are getting mature, I decided to take KVM workshop and some of the Open Virtualization Sessions on the summit.

Kernel-based Virtual Machine (KVM) is an open source hypervisor that provides enterprise-class performance, scalability and security to run Windows and Linux workloads.

To get started with KVM I used my work business class laptop, to avoid changing the internal encrypted Windows disk setup, I used an external USB 3 portable disk to perform a CentOS 6.5 Linux Install, selecting “Virtualization Tools” and “Virtualization Platform” group installs. Other popular distribution will also include these virtualization tools like Redhat, Fedora or Ubuntu.

For detailed instructions you can consult Kernel Based Virtual Machine project site.

Performance was very good during the workshop, running the main Linux CentOS image with KVM hypervisor installed, a small custom linux distribution provided by the Instructor as a guest operating system and from my side I installed a Desktop Debian 7.4 as guest operating system to put more stress workload on the setup. That was just one day testing, but I am happy with the initial results. In the future I will be doing more prove of concepts installs to push KVM technology to the limit and continue learning about it.

During the Linux Collaboration Summit Sessions – Open Virtualization track, the message I got from speakers and other attendees was that KVM is ready for business to virtualize Linux workloads in the datacenter.

Some Open Virtualization technologies with more active development that are using KVM foundation includes:

In addition to this, other virtualization technologies also mentioned on the Summit are:

That give us a lot of open source virtualization technologies to review, use and learn in the future.

In addition to the Open Virtualization staff I can mention that first day keynotes provided a very good overview about Linux development trends and good understanding on how open source community collaborate.

Others interesting sessions I was able to attend where about how to go from an Idea to a Corporate Sponsored Open Source Project and Open Source Compliance, between others.

In summary Linux Collaboration Summit was a great way to understand how Linux Kernel and Open Source community collaborate and I look forward to collaborate with them in the future.