When managing multiple Linux VMs with varying data growth patterns on VMware vSphere with SAN storage, thin provisioning becomes crucial yet challenging. The core issue emerges when sparse filesystems like ext3/4 unexpectedly consume allocated space despite containing minimal actual data.

Traditional filesystems like ext3/4 tend to scatter writes, causing premature storage allocation. Consider these alternatives:

# XFS often performs better for thin provisioning
mkfs.xfs /dev/sdX1

# For advanced features, consider btrfs with compression
mkfs.btrfs -m dup -d dup /dev/sdX1

Your approach of using LVM on thin-provisioned disks is sound. Here's a recommended implementation:

# Initial setup for 100GB volume on 500GB thin disk
pvcreate /dev/sdX
vgcreate vg_data /dev/sdX
lvcreate -L 100G -n lv_data vg_data
mkfs.xfs /dev/vg_data/lv_data

For existing VMs that have over-allocated, consider these reclamation methods:

# For VMFS datastores
vmkfstools --punchzero /vmfs/volumes/datastore/vm/vmdk.vmdk

# Filesystem-specific trimming
fstrim -v /mountpoint

While conventional wisdom suggests partitions, raw disks offer advantages in dynamic environments:

• Simpler expansion workflows
• No partition table overhead
• Direct alignment with storage subsystems

Implement proactive monitoring with this sample script:

#!/bin/bash
THRESHOLD=80
VGNAME="vg_data"

check_space() {
  local usage=$(vgs --units G --noheadings -o vg_free $VGNAME | awk '{print $1}')
  if (( $(echo "$usage > $THRESHOLD" | bc -l) )); then
    lvextend -r -L +10G /dev/$VGNAME/lv_data
  fi
}

For VMware-specific optimizations:

# ESXi advanced parameters to add in VMX file
scsi0:0.virtualSSD = 1
scsi0:0.ctkEnabled = "TRUE"
scsi0:0.ctkType = "thin"

When dealing with VMware virtual machines storing customer data, thin provisioning often doesn't behave as expected. The main issues stem from:

• Filesystem behavior (ext3/ext4 writing patterns)
• VMware's eager-zeroed vs lazy-zeroed thick provisioning
• LVM allocation policies

Traditional ext3/4 filesystems tend to fragment and expand virtual disks unnecessarily. Consider these alternatives:

# XFS often performs better for thin provisioning
mkfs.xfs /dev/mapper/vg0-lv_data

# Or for modern systems with TRIM support:
mkfs.ext4 -E discard /dev/mapper/vg0-lv_data

Your approach using LVM on thin-provisioned disks is sound. Here's a recommended setup sequence:

# Create physical volume on entire disk (no partition needed)
pvcreate /dev/sdb

# Create volume group with thin provisioning pool
vgcreate vg_thin /dev/sdb
lvcreate -L 100G --thinpool thinpool vg_thin

# Create thin volume
lvcreate -V 500G -T vg_thin/thinpool -n lv_data

For existing systems, implement regular space reclamation:

# For filesystems supporting TRIM/discard
fstrim -v /mnt/data

# VMware-specific UNMAP (ESXi 6.0+)
esxcli storage vmfs unmap --volume-uuid=[UUID]

Implement this Python script to monitor and alert on thin provision usage:

import subprocess
import smtplib

def check_thin_usage():
    result = subprocess.run(['lvs', '--units', 'g', '-o', 'lv_name,data_percent,pool_lv'],
                          capture_output=True, text=True)
    for line in result.stdout.splitlines()[1:]:
        name, percent, pool = line.split()
        if float(percent) > 80:
            send_alert(name, percent)

def send_alert(lv_name, usage):
    # Implementation omitted for brevity
    pass

check_thin_usage()

When growth is needed, follow this sequence:

1. Extend VMware virtual disk (hot-add supported)
2. Rescan SCSI bus: echo 1 > /sys/class/scsi_device/0\:0\:0\:0/device/rescan
3. Expand PV: pvresize /dev/sdb
4. Extend thin pool: lvextend -L +50G vg_thin/thinpool

While conventional wisdom suggests using partitions, in virtual environments with LVM, raw disks offer advantages:

• Simpler expansion workflow
• No partition table overhead
• Better alignment with thin provisioning concepts