NFS Share on Synology DS218+,

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hansB

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Sep 24, 2019
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I'm trying to connect my Proxmox server to a Synology NAS as datastore or backup target, but during initial setup of a new NSF Storage I got nothing by export browsing. when I try an showmount I see the export list but with extremely long delay.
I have only one physical network interface within a vmbr0, one untagged virtual interface and several tagged interfaces - both Devices are in the same Subnet and connected over a TP Link Switch

any ideas what's happen ?
 
Firewall?
 
Hi hansB,

The symptom you described—showmount eventually working but with a massive delay—could be a classic indicator of a DNS / Reverse DNS Resolution timeout.

NFS servers (like your Synology NAS) often try to perform a reverse DNS lookup to verify the hostname of the incoming client IP (your Proxmox node). If your DNS server isn't configured to handle these reverse queries for your local subnet, the NFS service will hang until the request times out before proceeding.

To verify and fix this, you can try the following:
  1. Test with /etc/hosts: SSH into your Synology NAS and add your Proxmox node's IP address and hostname to the /etc/hosts file.
    • Example: 192.168.1.100 pve-node-01
  2. Check Synology Settings: Alternatively, ensure that the Synology NAS can either reach a DNS server that knows about your PVE host, or that you have static entries mapped.
  3. Bypass DNS (if possible): Some users find success by disabling the "Name Service" or DNS-related lookups in the NFS configuration, but adding the entry to the hosts file is usually the most reliable quick fix.
If the delay disappears after adding the entry to /etc/hosts, then you've confirmed it's likely a DNS resolution issue!
 
pulipulichen said:
Hi hansB,

The symptom you described—showmount eventually working but with a massive delay—could be a classic indicator of a DNS / Reverse DNS Resolution timeout.

NFS servers (like your Synology NAS) often try to perform a reverse DNS lookup to verify the hostname of the incoming client IP (your Proxmox node). If your DNS server isn't configured to handle these reverse queries for your local subnet, the NFS service will hang until the request times out before proceeding.

To verify and fix this, you can try the following:
  1. Test with /etc/hosts: SSH into your Synology NAS and add your Proxmox node's IP address and hostname to the /etc/hostsfile.
    • Example: 192.168.1.100 pve-node-01
  2. Check Synology Settings: Alternatively, ensure that the Synology NAS can either reach a DNS server that knows about your PVE host, or that you have static entries mapped.
  3. Bypass DNS (if possible): Some users find success by disabling the "Name Service" or DNS-related lookups in the NFS configuration, but adding the entry to the hosts file is usually the most reliable quick fix.
If the delay disappears after adding the entry to /etc/hosts, then you've confirmed it's likely a DNS resolution issue!
Click to expand...
Which KI did you use to generate that answer?
 
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fstrankowski said:
Which KI did you use to generate that answer?
Click to expand...
You caught me!

Yes, I used AI to help polish and structure my English to ensure it was clear and easy to understand, as English is not my native language.

Regarding the technical advice I provided, I was simply trying to help based on general setup experiences. If my suggestions were off-track or if I misunderstood the specific problem hansB is facing, I would truly appreciate your guidance.

I’m here to learn as much as I am to help, so please let me know if there's a better way to troubleshoot this!
 
ok I guess that's not dns problem, because I use the ip address directly and my arp table shows the mac address referring hostname.
so what's about the firewall, so in my opinion both firewall are disabled on my Synology also the ddos prevention are off -

Code: 
root@pve:~# pve-firewall status
Status: disabled/running

why fw ? also unclear for me, firewalls generate no delay, ports are open or closed, or I'm wrong
relevant ports like sunrpc should be open in general, if I start nfs service ?
 
hansB said:
why fw ? also unclear for me, firewalls generate no delay, ports are open or closed, or I'm wrong
relevant ports like sunrpc should be open in general, if I start nfs service ?
Click to expand...
Depends on your firewall. There are firewalls which by default block all ports, others allow all traffic.
 
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