Synology NAS multipathing iSCSI connections to Proxmox

@clnx welcome to the forums! Great questions on Proxmox and iSCSI connections. First, take a look at my blog post on creating Proxmox iSCSI connections as I used a Synology NAS for this process as well: Proxmox iSCSI target to Synology NAS.

For multipathing, you will want to check out installing the package multipath-tools:

apt update
apt install multipath-tools

Once you have the package installed, you will want to edit the configuration file located here:

nano /etc/multipath.conf

You can create a general configuration using something like the following example:

defaults {
    user_friendly_names yes
    find_multipaths yes
}

blacklist {
    devnode "^sda"
}

devices {
    device {
        vendor "Synology"
        product ".*"
        path_grouping_policy group_by_prio
        path_checker tur
        rr_weight uniform
        no_path_retry queue
        failback immediate
    }
}

After you create the configuration file, you will need to restart the multipathing configuration:

systemctl restart multipathd

Discover your iSCSI target by IP addresses:

iscsiadm -m discovery -t sendtargets -p <target_IP>

Log into each target session:

iscsiadm -m node --login

After logging into the IP addresses with the above command, make sure multipath devices are created using the command:

multipath -ll

You should see a multipath device (will see something like "mpatha", etc) that combines both iSCSI paths.

Take a look at this official documentation here as well from Proxmox: Multipath - Proxmox VE.

Thank you for putting the time into this. I actually found https://pve.proxmox.com/wiki/Multipath and followed that document before seeing your post.  I had to resize my LVM as I had my Synology LUN set to 1G when it should have been 7T.  So, I have a multi-path iSCSI to Synology with MTU 9216.  Now I will try and create a new VM then try and import a VMWare VM.  Creating the LVM was a bit confusing with the multi-path until realized I was still choosing a Base Storage when it should be skipped and simply choose the new Volume group.

I am sure I will miss some VMWare/Vcenter stuff but excited to get this working.  Snapshots are probably going to be the most missed feature.