In this post, I’ll walk you through how I set up my Synology NAS to provide iSCSI storage for my Proxmox homelab environment. I recently decided to move my VM disks from an NFS share to an iSCSI LUN for better stability and performance. While NFS is easy to set up, I’ve experienced some VM crashes that led me to reconsider my storage backend. This guide will cover the entire process, from creating the LUN on Synology to migrating VM disks in Proxmox.
My Homelab Setup#
Before we dive in, here’s a quick overview of my current setup:
- Synology NAS: Running DSM with a single volume formatted with
ext4. Because of this, I can’t use ZFS over iSCSI, which would have been ideal for features like snapshots. If you’re starting from scratch and your NAS supports it, I highly recommend considering ZFS. - Network: A simple 1Gb/s Unifi switch. Both the NAS and the Proxmox server are single-homed, so I’m not using LACP (802.3ad) for link aggregation. This is a limitation for performance, as multipathing iSCSI would provide better throughput and redundancy.
- Proxmox: I’m running Proxmox VE 8.3.3 (Community Edition).
My goal is to create an iSCSI target on the Synology, use it to back an LVM (Logical Volume Manager) volume in Proxmox, and then move all my VM disks to this new, more robust storage.
Step 1: Configuring the Synology NAS#
First, we’ll configure the Synology. We need to create an iSCSI LUN and set up temporary permissions to allow Proxmox to connect.
In Synology SAN Manager#
Open SAN Manager from the DSM main menu.
1. Create a LUN#
A LUN (Logical Unit Number) is a block of storage we’ll present to Proxmox over the network.
- In SAN Manager, go to the LUN tab and click Create.
- You’ll be asked to choose between Thin Provisioning and Thick Provisioning.
- Thick Provisioning allocates all the space for the LUN immediately.
- Thin Provisioning allocates space on demand. It’s more space-efficient.
- I chose Thin Provisioning for flexibility. Follow the wizard to configure its size and properties.
2. Set Temporary Permissions#
To establish the initial connection, we’ll temporarily allow access from any initiator.
- Select the LUN you just created, go to the Host permissions, and set it to Allow all. We will tighten this later for security.
Step 2: Configuring Proxmox#
Now, let’s switch to the Proxmox web UI.
1. Add iSCSI Storage#
We’ll tell Proxmox where to find our iSCSI storage.
- Go to Datacenter > Storage and click Add > iSCSI.
- Enter your Synology’s IP address in the Portal field. Proxmox should automatically discover the target, and its IQN (iSCSI Qualified Name) will appear.
- Important: Uncheck the Use LUNs directly checkbox. This allows us to create an LVM on top of the iSCSI device, which is more flexible for managing multiple VM disks.
After adding, you’ll see the iSCSI device available to your Proxmox node.
2. Create an LVM Storage Pool#
Now we’ll create a storage pool using the iSCSI device.
- Go to Datacenter > Storage and click Add > LVM.
- Give the storage an ID (e.g.,
synology-iscsi-lvm). - Select the iSCSI device as the Base storage.
- Click Create.
Step 3: Migrating VM Disks#
With the new storage ready, we can move our VM disks.
- Select a VM and go to its Hardware tab.
- Select the VM disk, click Disk Action, and choose Move Storage.
- In the dialog, select your new LVM storage as the target and start the migration. You can opt to delete the original disk from the source storage automatically.
Repeat this for all VMs you want to move.
Step 4: Finalize Synology Security (Recommended)#
Once everything is working, we’ll go back to Synology to secure the iSCSI target.
1. Find Proxmox IQN#
First, you need the IQN of your Proxmox server (the initiator). You can find this in Proxmox under Datacenter > iSCSI.
2. Create a Host on Synology#
Now, create a “Host” on your Synology that represents your Proxmox server.
- In SAN Manager, go to Host and click Create.
- Give it a name and paste the Proxmox IQN you just copied.
3. Restrict LUN Access#
Finally, update the LUN permissions to only allow access from your Proxmox host.
- Go back to the LUN tab, select your LUN, and edit its Host permissions.
- Change the permission from “Allow all” to grant access exclusively to the Proxmox host you just created.
Conclusion#
That’s it! My Proxmox VM storage is now running on a more stable and robust iSCSI LUN from my Synology NAS. This setup provides a solid foundation, and while my 1Gbps network is a bottleneck for now, the storage itself is much improved over my previous NFS setup.
