245 lines
7.0 KiB
Markdown
245 lines
7.0 KiB
Markdown
## Purpose
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This document describes the **end-to-end procedure** for creating a **thick-provisioned iSCSI-backed shared storage target** on **TrueNAS CORE**, and consuming it from a **Proxmox VE cluster** using **shared LVM**.
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This approach is intended to:
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- Provide SAN-style block semantics
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- Enable Proxmox-native snapshot functionality (LVM volume chains)
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- Avoid third-party plugins or middleware
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- Be fully reproducible via CLI
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## Assumptions
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- TrueNAS **CORE** (not SCALE)
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- ZFS pool already exists and is healthy
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- SSH service is enabled on TrueNAS
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- Proxmox VE nodes have network connectivity to TrueNAS
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- iSCSI traffic is on a reliable, low-latency network (10GbE recommended)
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- All VM workloads are drained from at least one Proxmox node for maintenance
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!!! note "Proxmox VE Version Context"
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This guide assumes **Proxmox VE 9.1.4 (or later)**. Snapshot-as-volume-chain support on shared LVM (e.g., iSCSI) is available and improved, including enhanced handling of vTPM state in offline snapshots.
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!!! warning "Important"
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`volblocksize` **cannot be changed after zvol creation**. Choose carefully.
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## Target Architecture
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```
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ZFS Pool
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└─ Zvol (Thick / Reserved)
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└─ iSCSI Extent
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└─ Proxmox LVM PV
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└─ Shared VG
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└─ VM Disks
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```
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## Create a Dedicated Zvol for Proxmox
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### Variables
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Adjust as needed before execution.
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```sh
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POOL_NAME="CLUSTER-STORAGE"
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ZVOL_NAME="iscsi-storage"
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ZVOL_SIZE="14T"
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VOLBLOCKSIZE="16K"
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```
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### Create the Zvol (Thick-Provisioned)
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```sh
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zfs create -V ${ZVOL_SIZE} \
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-o volblocksize=${VOLBLOCKSIZE} \
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-o compression=lz4 \
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-o refreservation=${ZVOL_SIZE} \
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${POOL_NAME}/${ZVOL_NAME}
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```
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!!! note
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The `refreservation` enforces **true thick provisioning** and prevents overcommit.
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## Configure iSCSI Target (TrueNAS CORE)
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This section uses a **hybrid approach**:
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- **CLI** is used for ZFS and LUN (extent backing) creation
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- **TrueNAS GUI** is used for iSCSI portal, target, and association
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- **CLI** is used again for validation
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### Enable iSCSI Service
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```sh
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service ctld start
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sysrc ctld_enable=YES
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```
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### Create the iSCSI LUN Backing (CLI)
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This step creates the **actual block-backed LUN** that will be exported via iSCSI.
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```sh
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# Sanity check: confirm the backing zvol exists
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ls -l /dev/zvol/${POOL_NAME}/${ZVOL_NAME}
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# Create CTL LUN backed by the zvol
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ctladm create -b block \
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-o file=/dev/zvol/${POOL_NAME}/${ZVOL_NAME} \
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-S ISCSI-STORAGE \
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-d ISCSI-STORAGE
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```
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### Verify the LUN is real and correctly sized
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```sh
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ctladm devlist -v
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```
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!!! tip
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`Size (Blocks)` must be **non-zero** and match the zvol size. If it is `0`, stop and correct before proceeding.
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### Configure iSCSI Portal, Target, and Extent Association (CLI Only)
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!!! warning "Do NOT Use the TrueNAS iSCSI GUI"
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**Once you choose a CLI-managed iSCSI configuration, the TrueNAS Web UI must never be used for iSCSI.**
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Opening or modifying **Sharing → Block Shares (iSCSI)** in the GUI will **overwrite CTL runtime state**, invalidate manual `ctladm` configuration, and result in targets that appear correct but expose **no LUNs** to initiators.
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**This configuration is CLI-owned and CLI-managed.**
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- Do **not** add, edit, or view iSCSI objects in the GUI
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- Do **not** use the iSCSI wizard
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- Do **not** mix GUI extents with CLI-created LUNs
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#### Create iSCSI Portal (Listen on All Interfaces)
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```sh
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# Backup any existing ctl.conf
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cp -av /etc/ctl.conf /etc/ctl.conf.$(date +%Y%m%d-%H%M%S).bak 2>/dev/null || true
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# Write a clean /etc/ctl.conf
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cat > /etc/ctl.conf <<'EOF'
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# --- Bunny Lab: Proxmox iSCSI (CLI-only) ---
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auth-group "no-auth" {
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auth-type none
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initiator-name "iqn.1993-08.org.debian:01:5b963dd51f93" # cluster-node-01 ("cat /etc/iscsi/initiatorname.iscsi")
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initiator-name "iqn.1993-08.org.debian:01:1b4df0fa3540" # cluster-node-02 ("cat /etc/iscsi/initiatorname.iscsi")
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initiator-name "iqn.1993-08.org.debian:01:5669aa2d89a2" # cluster-node-03 ("cat /etc/iscsi/initiatorname.iscsi")
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}
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# Listen on all interfaces on the default iSCSI port
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portal-group "pg0" {
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listen 0.0.0.0:3260
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discovery-auth-group "no-auth"
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}
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# Create a target IQN
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target "iqn.2026-01.io.bunny-lab:storage" {
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portal-group "pg0"
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auth-group "no-auth"
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# Export LUN 0 backed by the zvol device
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lun 0 {
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path /dev/zvol/CLUSTER-STORAGE/iscsi-storage
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serial "ISCSI-STORAGE"
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device-id "ISCSI-STORAGE"
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}
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}
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EOF
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# Restart ctld to apply the configuration file
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service ctld restart
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# Verify the iSCSI listener is actually up
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sockstat -4l | grep ':3260'
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# Verify CTL now shows an iSCSI frontend
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ctladm portlist -v | egrep -i '(^Port|iscsi|listen=)'
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```
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!!! success
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At this point, the iSCSI target is live and correctly exposing a block device to initiators. You may now proceed to **Connect from ProxmoxVE Nodes** section.
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## Connect from ProxmoxVE Nodes
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Perform the following **on each Proxmox node**.
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```sh
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# Install iSCSI Utilities
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apt update
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apt install -y open-iscsi lvm2
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# Discover Target
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iscsiadm -m discovery -t sendtargets -p <TRUENAS_IP>
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# Log In
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iscsiadm -m node --login
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# Rescan SCSI Bus
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iscsiadm -m session -P 3
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### Verify Device
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# If everything works successfully, you should see something like "sdi 8:128 0 8T 0 disk".
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lsblk
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```
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## Create Shared LVM (Execute on One Node Only)
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!!! warning "Important"
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**Only run LVM creation on ONE node**. All other nodes will only scan.
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```sh
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# Initialize Physical Volume
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pvcreate /dev/sdX
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# Create Volume Group
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vgcreate vg_proxmox_iscsi /dev/sdX
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```
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## Register Storage in Proxmox
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### Rescan LVM (Other Nodes)
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```sh
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pvscan
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vgscan
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```
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### Add Storage (GUI)
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**Datacenter → Storage → Add → LVM**
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- ID: `iscsi-cluster-lvm`
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- Volume Group: `vg_proxmox_iscsi`
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- Content: `Disk image, Container`
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- Shared: ✔️
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- Allow Snapshots as Volume-Chain: ✔️
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## Validation
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- Snapshot create / revert / delete
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- Live migration between nodes
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- PBS backup and restore test
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!!! success
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If all validation tests pass, the storage is production-ready.
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## Expanding iSCSI Storage (No Downtime)
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If you need to expand the storage space of the newly-created iSCSI LUN, you can run the ZFS commands seen below on the TrueNAS Core server. The first command increases the size, the second command pre-allocated the space (thick-provisioned).
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!!! warning "ProxmoxVE Cluster-specific Notes"
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- `pvresize` must be executed on **exactly one** ProxmoxVE node.
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- All other nodes should only perform `pvscan` / `vgscan` after the resize.
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- Running `pvresize` on multiple nodes can corrupt shared LVM metadata.
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```sh
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# Expand Zvol (TrueNAS)
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zfs set volsize=16T CLUSTER-STORAGE/iscsi-storage
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zfs set refreservation=16T CLUSTER-STORAGE/iscsi-storage
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service ctld restart
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# Rescan the block device on all ProxmoxVE nodes
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echo 1 > /sys/class/block/sdX/device/rescan
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# Verify on all nodes that the new size is displayed
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lsblk /dev/sdX
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# Run this on only ONE of the ProxmoxVE nodes.
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pvresize /dev/sdX
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# Rescan on the other nodes that you did not run the pvresize command on. They will now see the expanded free space.
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pvscan
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vgscan
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``` |