lvm senario

fs

overview

create LVs

If you want to create three Logical Volumes (LVs) of sizes 1TB, 1TB, and 5TB on a single Volume Group (VG) for each disk, here’s how you can do it step by step.

Assume:

​ • Disks: /dev/nvme0n1, /dev/nvme1n1, /dev/nvme2n1

​ • Volume Groups: vg_nvme0, vg_nvme1, vg_nvme2

​ • Logical Volumes (LVs): lv1, lv2, lv3 for each VG

​ • LV Sizes: 1TB, 1TB, and 5TB

1. Create Physical Volumes (PVs)

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# Initialize each disk as a PV:
sudo pvcreate /dev/nvme0n1
sudo pvcreate /dev/nvme1n1
sudo pvcreate /dev/nvme2n1

2. Create Volume Groups (VGs)

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# Create a VG for each disk:
sudo vgcreate vg_nvme0 /dev/nvme0n1
sudo vgcreate vg_nvme1 /dev/nvme1n1
sudo vgcreate vg_nvme2 /dev/nvme2n1

3. Create Logical Volumes (LVs)

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# Allocate 1TB, 1TB, and 5TB LVs from each VG.

# For vg_nvme0:
sudo lvcreate -L 1T -n lv1 vg_nvme0
sudo lvcreate -L 1T -n lv2 vg_nvme0
sudo lvcreate -L 5T -n lv3 vg_nvme0

# For vg_nvme1:
sudo lvcreate -L 1T -n lv1 vg_nvme1
sudo lvcreate -L 1T -n lv2 vg_nvme1
sudo lvcreate -L 5T -n lv3 vg_nvme1

# For vg_nvme2:
sudo lvcreate -L 1T -n lv1 vg_nvme2
sudo lvcreate -L 1T -n lv2 vg_nvme2
sudo lvcreate -L 5T -n lv3 vg_nvme2

4. Verify the Setup

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# Check the LVs and their sizes:
sudo lvs

You should see something like:

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LV   VG        Attr       LSize

lv1  vg_nvme0  -wi-a----- 1.00t                           
lv2  vg_nvme0  -wi-a----- 1.00t                           
lv3  vg_nvme0  -wi-a----- 5.00t                           
lv1  vg_nvme1  -wi-a----- 1.00t                           
lv2  vg_nvme1  -wi-a----- 1.00t                           
lv3  vg_nvme1  -wi-a----- 5.00t                           
lv1  vg_nvme2  -wi-a----- 1.00t                           
lv2  vg_nvme2  -wi-a----- 1.00t                           
lv3  vg_nvme2  -wi-a----- 5.00t

5. Format the LVs

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# Use xfs or another filesystem to format the LVs:
sudo mkfs.xfs /dev/vg_nvme0/lv1
sudo mkfs.xfs /dev/vg_nvme0/lv2
sudo mkfs.xfs /dev/vg_nvme0/lv3

sudo mkfs.xfs /dev/vg_nvme1/lv1
sudo mkfs.xfs /dev/vg_nvme1/lv2
sudo mkfs.xfs /dev/vg_nvme1/lv3

sudo mkfs.xfs /dev/vg_nvme2/lv1
sudo mkfs.xfs /dev/vg_nvme2/lv2
sudo mkfs.xfs /dev/vg_nvme2/lv3

6. Mount the LVs

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# Create directories for each LV and mount them:
sudo mkdir -p /mnt/nvme0/lv1 /mnt/nvme0/lv2 /mnt/nvme0/lv3
sudo mkdir -p /mnt/nvme1/lv1 /mnt/nvme1/lv2 /mnt/nvme1/lv3
sudo mkdir -p /mnt/nvme2/lv1 /mnt/nvme2/lv2 /mnt/nvme2/lv3

sudo mount /dev/vg_nvme0/lv1 /mnt/nvme0/lv1
sudo mount /dev/vg_nvme0/lv2 /mnt/nvme0/lv2
sudo mount /dev/vg_nvme0/lv3 /mnt/nvme0/lv3

sudo mount /dev/vg_nvme1/lv1 /mnt/nvme1/lv1
sudo mount /dev/vg_nvme1/lv2 /mnt/nvme1/lv2
sudo mount /dev/vg_nvme1/lv3 /mnt/nvme1/lv3

sudo mount /dev/vg_nvme2/lv1 /mnt/nvme2/lv1
sudo mount /dev/vg_nvme2/lv2 /mnt/nvme2/lv2
sudo mount /dev/vg_nvme2/lv3 /mnt/nvme2/lv3

7. Persist the Mounts

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# Add the mounts to /etc/fstab for automatic remounting on boot:
echo '/dev/vg_nvme0/lv1 /mnt/nvme0/lv1 xfs defaults 0 0' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme0/lv2 /mnt/nvme0/lv2 xfs defaults 0 0' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme0/lv3 /mnt/nvme0/lv3 xfs defaults 0 0' | sudo tee -a /etc/fstab

echo '/dev/vg_nvme1/lv1 /mnt/nvme1/lv1 xfs defaults 0 0' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme1/lv2 /mnt/nvme1/lv2 xfs defaults 0 0' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme1/lv3 /mnt/nvme1/lv3 xfs defaults 0 0' | sudo tee -a /etc/fstab

echo '/dev/vg_nvme2/lv1 /mnt/nvme2/lv1 xfs defaults 0 0' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme2/lv2 /mnt/nvme2/lv2 xfs defaults 0 0' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme2/lv3 /mnt/nvme2/lv3 xfs defaults 0 0' | sudo tee -a /etc/fstab
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# **Final Directory Layout**
# **Disk**	**VG Name**	**LV Name**	**Size**	**Mount Point**
/dev/nvme0n1	vg_nvme0	lv1	1T	/mnt/nvme0/lv1
		lv2	1T	/mnt/nvme0/lv2
		lv3	5T	/mnt/nvme0/lv3

/dev/nvme1n1	vg_nvme1	lv1	1T	/mnt/nvme1/lv1
		lv2	1T	/mnt/nvme1/lv2
		lv3	5T	/mnt/nvme1/lv3

/dev/nvme2n1	vg_nvme2	lv1	1T	/mnt/nvme2/lv1
		lv2	1T	/mnt/nvme2/lv2
		lv3	5T	/mnt/nvme2/lv3

defaults 0 x

The difference is in the last number (0 vs 2) in the fstab entry, which represents the filesystem check (fsck) pass number. Here’s what these numbers mean:

Last field (6th field) in fstab:

  • 0 = No filesystem check will be done at boot time
  • 1 = Filesystem will be checked first (typically used for root filesystem /)
  • 2 = Filesystem will be checked after pass 1 filesystems (typically used for other filesystems)

So:

  • defaults 0 0 means the filesystem will never be automatically checked during boot
  • defaults 0 2 means the filesystem will be checked during boot, but after the root filesystem

Best practices:

  • Use 0 1 for the root filesystem (/)
  • Use 0 2 for other important filesystems that should be checked
  • Use 0 0 for pseudo-filesystems (like proc, sysfs) or filesystems that don’t need checking (like swap)

wipe disk and create lvm

assum dev is /dev/nvme2n1

To erase all partitions on the device /dev/nvme2n1 and create multiple logical volumes (LVs) using the LVM framework, follow these steps:

1. Verify Device and Backup Data

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# Ensure you are working on the correct device. Erasing partitions will delete all data on the device.
sudo lsblk -o NAME,SIZE,TYPE,MOUNTPOINT /dev/nvme2n1

2. Erase Existing Partitions

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# Clear the Partition Table, To wipe the partition table completely:
sudo wipefs -a /dev/nvme2n1

# Verify the Disk is Clean, Check that no partitions remain
sudo lsblk /dev/nvme2n1

3. Create Physical Volume (PV)

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# Convert the entire disk into an LVM physical volume:
sudo pvcreate /dev/nvme2n1

# Verify the PV
sudo pvdisplay

4. Create Volume Group (VG)

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# Create a volume group that spans the entire disk:
sudo vgcreate vg_nvme2n1 /dev/nvme2n1

# Verify the VG:
sudo vgdisplay

5. Create Logical Volumes (LVs)

Example: Create Three LVs

​ • LV1: 1TB

​ • LV2: 1TB

​ • LV3: Remaining space

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sudo lvcreate -L 1T -n lv1 vg_nvme2n1
sudo lvcreate -L 1T -n lv2 vg_nvme2n1
sudo lvcreate -l 100%FREE -n lv8 vg_nvme2n1 --wipesignatures y
# 注意如果在lvcreate的时候一直提示 warning wipe offset xxx,那执行 sudo lvcreate xxx -y (加-y参数)

# Verify the LVs:
sudo lvdisplay

6. Format Logical Volumes

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# Format each logical volume with your desired file system (e.g., XFS):
sudo mkfs.xfs /dev/vg_nvme2n1/lv1

sudo mkfs.xfs /dev/vg_nvme2n1/lv2

sudo mkfs.xfs /dev/vg_nvme2n1/lv3

7. Mount Logical Volumes

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# Create mount points and mount the LVs:
sudo mkdir -p /mnt/nvme2n1/lv1 /mnt/nvme2n1/lv2 /mnt/nvme2n1/lv3

sudo mount /dev/vg_nvme2n1/lv1 /mnt/nvme2n1/lv1
sudo mount /dev/vg_nvme2n1/lv2 /mnt/nvme2n1/lv2
sudo mount /dev/vg_nvme2n1/lv3 /mnt/nvme2n1/lv3
# Verify the mounts:
df -h

8. Make the Mounts Persistent

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# Add entries to /etc/fstab to ensure the LVs are mounted on reboot:
echo '/dev/vg_nvme2n1/lv1 /mnt/nvme2n1/lv1 xfs defaults 0 2' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme2n1/lv2 /mnt/nvme2n1/lv2 xfs defaults 0 2' | sudo tee -a /etc/fstab
echo '/dev/vg_nvme2n1/lv3 /mnt/nvme2n1/lv3 xfs defaults 0 2' | sudo tee -a /etc/fstab