Server Disk Expansion Plan – Expanding / (Root Filesystem)

Objective

Expand the root (/) filesystem by adding a new disk while ensuring system stability and minimal downtime.

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Pre-Expansion Activities

1. Backup Strategy (Critical Step)

Ensure data safety before making changes.

✅ Application Backup (Handled by our team)
✅ Database Backup (Handled by our team)
✅ OS Backup (Handled by the client)

2. Verify Current Disk Space & Layout

Run the following commands to analyze disk usage and partitioning:

df -h
lsblk
fdisk -l
mount | grep "on / "

• Confirm the current root filesystem type (ext4, XFS, etc.).
• Identify whether / is on LVM or a standard partition.

3. Check Active Services & Dependencies

• Identify critical services running on /:

  systemctl list-units --type=service --state=running

• Inform stakeholders of any potential downtime.

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Disk Expansion Execution

Step 1: Add & Verify the New Disk

1. After attaching the new disk, confirm its detection:

   lsblk
   dmesg | tail
   fdisk -l

   Assume the new disk is /dev/sdb (adjust based on your system).

Step 2: Expanding / Based on Current Setup

A. If Root (/) is on LVM (Recommended Method)

1. Create a Physical Volume (PV) on the New Disk

   pvcreate /dev/sdb

2. Extend the Volume Group (VG)

   vgextend vg_root /dev/sdb

3. Extend the Logical Volume (LV)

   lvextend -l +100%FREE /dev/vg_root/lv_root

4. Resize the Root Filesystem
   • For ext4:

     resize2fs /dev/vg_root/lv_root

   • For XFS:

     xfs_growfs /

5. Verify Expansion

   df -h /

B. If Root (/) is on a Standard Partition (Non-LVM)

⚠ This method may require a reboot and booting into a live environment.

1. Check Current Partitioning Scheme

   fdisk -l

2. Expand the Root Partition
   • Use fdisk, parted, or growpart:

     growpart /dev/sda 1  # Adjust partition number as needed

3. Resize the Filesystem
   • For ext4:

     resize2fs /dev/sda1

   • For XFS:

     xfs_growfs /

4. Reboot (If Required)

   reboot

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Post-Expansion Verification

1. Validate Expansion

df -h /
lsblk

2. Check Application & Database Functionality

Restart necessary services and validate operations:

systemctl restart <service>

3. Monitor Logs for Errors

dmesg | tail -50
journalctl -xe

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Rollback Plan (In Case of Failure)

• If issues arise, boot into a live environment and restore from backup.
• For LVM errors, revert changes using:

  vgcfgrestore vg_root

• Run fsck if filesystem corruption occurs.

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Final Steps

✅ Update documentation on disk changes.
✅ Notify stakeholders that expansion is complete.
✅ Monitor disk performance over the next few days.

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Expected Outcome

• / (root) successfully expanded with additional disk space.
• No service disruptions or data loss.