Sankofa/docs/ceph/FREE_DRIVE_FROM_UBUNTU_VG.md

Free Drive from ubuntu-vg for Ceph OSD

Date: 2025-12-13
Status: 🔍 250GB DRIVES FOUND IN ubuntu-vg VOLUME GROUP

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Current Situation

The verification revealed:

• ✅ 6x 250GB drives ARE detected (sdc, sde, sdh, and others)
• ⚠️ They're in ubuntu-vg volume group (100% allocated)
• ✅ User confirmed: 2 drives need to be formatted
• 🎯 Goal: Free up one drive for third Ceph OSD

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Step-by-Step: Free Drive from ubuntu-vg

Step 1: Check Current Status

Run the check script on R630-01:

bash /tmp/check-ubuntu-vg-and-prepare-osd.sh

Or manually:

# Check ubuntu-vg status
vgs ubuntu-vg
lvs ubuntu-vg
pvs | grep ubuntu-vg

# Check what's mounted
mount | grep ubuntu-vg
df -h | grep ubuntu-vg

Step 2: Identify Drive to Free

From the screenshot, drives in ubuntu-vg include:

• /dev/sdc3 (247.90 GB)
• /dev/sde3 (247.90 GB)
• /dev/sdh3 (247.90 GB)
• At least one more (partially visible)

Choose one drive that's safe to remove (preferably one that's not critical).

Step 3: Unmount and Remove from ubuntu-vg

WARNING: This will destroy data on the logical volume!

# 1. Unmount any mounted logical volumes (if any)
umount /dev/ubuntu-vg/* 2>/dev/null || true

# 2. Deactivate the volume group
vgchange -a n ubuntu-vg

# 3. Remove the physical volume from ubuntu-vg
# Replace sdX with your chosen drive (e.g., sdc, sde, sdh)
pvremove /dev/sdX3

# 4. If you want to remove the entire ubuntu-vg (if not needed):
# vgremove ubuntu-vg

Step 4: Wipe the Drive

WARNING: This destroys all data on the drive!

# Wipe filesystem signatures
wipefs -a /dev/sdX

# Optionally, zero out the beginning (for clean slate)
dd if=/dev/zero of=/dev/sdX bs=1M count=100

Step 5: Create Ceph OSD

# Create Ceph OSD on the freed drive
# Replace sdX with your drive (e.g., sdc, sde, sdh)
ceph-volume lvm create --data /dev/sdX

Step 6: Verify OSD Created

# Check OSD tree (should show 3 OSDs now)
ceph osd tree

# Check Ceph health (should improve)
ceph health
ceph health detail

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Alternative: If ubuntu-vg is Needed

If ubuntu-vg contains important data:

Option 1: Backup and Remove One Drive

1. Backup data from ubuntu-vg
2. Reduce ubuntu-vg to remove one drive
3. Use freed drive for Ceph OSD

Option 2: Use Different Drive

If 2 drives need formatting (as user mentioned):

• Use one of those 2 drives for Ceph OSD
• Format the other as needed

Option 3: Shrink ubuntu-vg

1. Shrink logical volume in ubuntu-vg
2. Remove one physical volume from ubuntu-vg
3. Use freed drive for Ceph OSD

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Quick Commands Reference

# Check ubuntu-vg
vgs ubuntu-vg
lvs ubuntu-vg
pvs | grep ubuntu-vg

# Check what's using it
mount | grep ubuntu-vg
lsof | grep ubuntu-vg

# Remove drive from ubuntu-vg (WARNING: Destroys data!)
vgchange -a n ubuntu-vg
pvremove /dev/sdX3

# Wipe drive
wipefs -a /dev/sdX

# Create Ceph OSD
ceph-volume lvm create --data /dev/sdX

# Verify
ceph osd tree
ceph health

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Safety Checklist

Before removing a drive from ubuntu-vg:

• Backup any important data (if ubuntu-vg contains data)
• Verify ubuntu-vg is not critical for system operation
• Check if logical volumes are mounted (unmount first)
• Confirm which drive to remove (choose carefully)
• Have recovery plan if something goes wrong

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Expected Results

Before

• 2 OSDs (insufficient for 3-way replication)
• HEALTH_WARN: TOO_FEW_OSDS

After

• 3 OSDs (sufficient for 3-way replication)
• HEALTH_OK or improved (TOO_FEW_OSDS warning gone)
• VMs can be created with ceph-fs storage

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Summary

Current State

• ✅ 6x 250GB drives found in ubuntu-vg
• ⚠️ All drives 100% allocated
• 🎯 Need to free one drive for Ceph OSD

Action Required

1. Check ubuntu-vg status
2. Identify safe drive to remove
3. Remove from ubuntu-vg (if safe)
4. Wipe and create Ceph OSD
5. Verify Ceph health improves

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Last Updated: 2025-12-13
Status: 🔍 READY TO FREE DRIVE FROM ubuntu-vg