§2024-07-08

Correct, using LVM with RAID 0 does not provide redundancy. RAID 0 is used for performance by striping data across multiple disks, but if one disk fails, all data in the array is lost. To have redundancy along with LVM, consider using RAID 1 (mirroring) or RAID 5/6 (striping with parity).

However, if you still want to extend your /var partition with a RAID 0 setup using LVM, follow these steps:

Prerequisites

• Ensure you have backups of your data.
• Ensure mdadm (the software RAID management tool) is installed:

  sudo apt-get install mdadm
  

Steps

1. Prepare the New Disks: Partition /dev/sda2 and /dev/sdb1 (or any other disks you want to use in the RAID 0 array).

   sudo fdisk /dev/sda
   

   • Use n to create a new partition.
   • Select the partition number (e.g., 2).
   • Specify the start and end (default values should be fine if you're using the entire space).
   • Use t to change the partition type to fd (Linux RAID autodetect).
   • Use w to write the changes.

   Repeat the process for /dev/sdb to create /dev/sdb1.

2. Create a New RAID 0 Array:

   sudo mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sda2 /dev/sdb1
   

3. Create a Physical Volume (PV) on the RAID device:

   sudo pvcreate /dev/md0
   

4. Extend the Volume Group (VG): Add the new RAID device to your existing volume group.

   sudo vgextend <VG Name> /dev/md0
   

5. Extend the Logical Volume (LV): Identify the logical volume for /var and extend it to include the new space.

   sudo lvextend -l +100%FREE <LV Path>
   

6. Resize the Filesystem: Finally, resize the filesystem to use the newly allocated space.

   sudo resize2fs <LV Path>
   

Example

Assuming the VG name is vg0 and the LV path is /dev/vg0/var:

sudo mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sda2 /dev/sdb1
sudo pvcreate /dev/md0
sudo vgextend vg0 /dev/md0
sudo lvextend -l +100%FREE /dev/vg0/var
sudo resize2fs /dev/vg0/var

Verifying

You can verify the changes by checking the disk space:

df -h /var

This should show the increased size for /var.

Notes

• Be cautious with RAID 0 as it offers no redundancy; if one drive fails, all data in the array is lost.
• The exact commands may vary slightly based on your Linux distribution.
• Ensure no processes are using /var heavily during this operation to avoid issues.

If you require redundancy, consider using RAID 1, RAID 5, or RAID 6 setups, which can be integrated with LVM to provide both redundancy and flexibility.