Complete Guide on Extending LVM with a New Disk and Reconfiguring OS Disk

Complete Guide on Extending LVM with a New Disk and Reconfiguring OS Disk.md

Complete Guide on Extending LVM with a New Disk and Reconfiguring OS Disk

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Step 1: Scan for New Disks

To detect newly added disks without rebooting, use the following command:

echo "- - -" > /sys/class/scsi_host/host32/scan

Replace host32 with the appropriate host number if different on your system.

Step 2: Prepare the New Disk

Create a physical volume on the new disk:

sudo pvcreate /dev/sdx  # Replace /dev/sdx with your new disk identifier

Step 3: Extend Volume Group

Add the new physical volume to your existing volume group:

sudo vgextend your-vg-name /dev/sdx  # Replace your-vg-name and /dev/sdx appropriately

Step 4: Extend Logical Volume

Allocate the newly available space to the logical volume:

sudo lvextend -l +100%FREE /dev/your-vg-name/your-lv-name  # Replace with your volume group and logical volume names

Step 5: Resize the Filesystem

Resize the filesystem to use the new space on the logical volume:

sudo resize2fs /dev/your-vg-name/your-lv-name  # Adjust as necessary, assuming an ext4 filesystem

Step 6: Copying Data to the New Logical Volume

Before manipulating /var, ensure all data is backed up and services that write to /var are stopped:

sudo systemctl stop nginx zabbix-server grafana-server prometheus

Mount the new logical volume temporarily to /mnt and copy all data:

sudo mount /dev/your-vg-name/your-lv-name /mnt
sudo rsync -avxHAX /var/ /mnt/

Update /etc/fstab to use the new logical volume for /var:

# Open /etc/fstab with an editor, e.g., nano
sudo nano /etc/fstab
# Add or modify the line for /var
/dev/your-vg-name/your-lv-name /var ext4 defaults 0 2

Unmount and remount to verify:

sudo umount /mnt
sudo mount -a

Restart the stopped services:

sudo systemctl start nginx zabbix-server grafana-server prometheus

Step 7: Deleting an OS Disk Partition and Adding to LVM

a. Delete the Partition

Using fdisk or parted, remove the OS disk partition (e.g., /dev/sda3):

sudo fdisk /dev/sda

In fdisk, use d to delete and w to write changes to the disk.

b. Update the Kernel's Partition Table

Inform the kernel of the changes to the partition table:

sudo partprobe /dev/sda

c. Create a Physical Volume

Once the partition is deleted, convert it into a physical volume:

sudo pvcreate /dev/sda3

d. Extend the Volume Group and Logical Volume

Extend your volume group and logical volume as described in Steps 3 and 4.

Step 8: Verify Changes

Check the new size of the filesystem:

df -h /var

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# Rescan Disk in Linux

If you have added additional space to a disk (e.g., `sdb`) and want to rescan it, follow these steps:

## 1. Rescan the SCSI Bus for the Disk

```bash
echo 1 > /sys/class/block/sdb/device/rescan

2. Rescan the SCSI Host (if the above command doesn't work)

echo "- - -" > /sys/class/scsi_host/host32/scan

• Make sure host32 corresponds to the correct SCSI host for your sdb disk. You can list the available hosts using the following command:

ls /sys/class/scsi_host/

3. Verify the Updated Disk Information

After rescanning, check if the disk sdb reflects the updated size:

lsblk

4. Expand the Partition (if applicable)

If you need to expand a partition on the disk, use a partitioning tool like fdisk or parted to resize the partition.

5. Resize the Filesystem (if applicable)

If you have an existing filesystem on the partition, resize it to utilize the new space. For example, for an ext4 filesystem:

resize2fs /dev/sdb1

This process should help update the disk to reflect the added space and make it available for use.

# Extend an LVM Logical Volume

If you have created or extended a physical volume (for example, `/dev/sdb2`) and added it to an existing volume group (such as `vgdata`), follow these steps to grow a logical volume (for example, `lvdata`) to use the newly available space.

## 1. Check Available Free Space in the Volume Group

```bash
vgs

This command shows the volume groups and how much free space (VFree) is available.

2. Extend the Logical Volume

Use the free space in vgdata to extend lvdata. To use all available free space:

lvextend -l +100%FREE /dev/vgdata/lvdata

If you only want to extend by a specific size (e.g., 200GB), use:

lvextend -L +200G /dev/vgdata/lvdata

3. Resize the Filesystem

After extending the LV, resize the filesystem to make use of the additional space.

If Using ext4:

resize2fs /dev/vgdata/lvdata

If Using XFS:

xfs_growfs /mountpoint

Replace /mountpoint with the actual mount location of /dev/vgdata/lvdata.

4. Verify the New Size

Check the filesystem size:

df -hT /mountpoint

Optionally, confirm the updated logical volume size:

lvdisplay /dev/vgdata/lvdata

You should now see the extended size of your logical volume and filesystem.