HI, I have two unraid servers, NAS and NASBACKUP.

I am trying to move all data from NAS -> NASBACKUP by mounting the backup server as a SMB mount on NAS. Then using FreeFileSync docker to move the data. There is a large amount of data to move, about ~100 TB.

The problem is the connection is not reliable. I get random CIF drops all the time like this:

Nov 14 16:51:58 nas kernel: CIFS: VFS: \\NASBACKUP.LAN.LOCAL sends on sock 0000000032302d62 stuck for 15 seconds

Nov 14 16:53:00 nas kernel: CIFS: VFS: \\NASBACKUP.LAN.LOCAL Send error in SessSetup = -11

Sometimes I can go 24 hours without an error, sometimes I get them within minutes of mounting. I can't tell what server the problem lies in, but i've attached diags from both of them. Even giving each server a separate NIC and directly attaching them gives the same behavior. Unfortunately, FreeFilySync does not gracefully recover from this and requires manual intervention every time this happens. It's greatly slowing down my backup progress.

nas-diagnostics-20251114-1653.zip nasbackup-diagnostics-20251114-1654.zip

for linux to linux it better to use nfs... or sftp over ssh

Edited November 15, 2025Nov 15 by bmartino1

I personaly prefer to use sftp...

filezila linux server docker and sftp docker in teh CA....

10 minutes ago, bmartino1 said:

for linux to linux it better to use nfs... or sftp over ssh

i did try NFS as well and saw similar behavior, it eventually dropped the connection and FFS also errored out. i even tried rsync instead of FFS and unfortunately the same behavior. it just freezes when the error happens instead of gracefully reconnecting. i can't trace down WHY this is happening, is it just stressed under constant load?

1 hour ago, oliver said:

i did try NFS as well and saw similar behavior, it eventually dropped the connection and FFS also errored out. i even tried rsync instead of FFS and unfortunately the same behavior. it just freezes when the error happens instead of gracefully reconnecting. i can't trace down WHY this is happening, is it just stressed under constant load?

It could be. Usually it's faulty cable and switch disconnect due to packets...

Using another device something like wires shark to capture what's happening and when would be needed.

Unless you running on some old old hardware or the nic is not 1 gb min for its nice option ROM. While server load and stress could be a cause. It not what seem to be the issue at hand.

I would suspect some weird network issues and disconnect first.

This is one reason why I prefer to use filezila and sftp to be able to resume pause save and continue transfers.

16 hours ago, bmartino1 said:

It could be. Usually it's faulty cable and switch disconnect due to packets...

Using another device something like wires shark to capture what's happening and when would be needed.

Unless you running on some old old hardware or the nic is not 1 gb min for its nice option ROM. While server load and stress could be a cause. It not what seem to be the issue at hand.

I would suspect some weird network issues and disconnect first.

This is one reason why I prefer to use filezila and sftp to be able to resume pause save and continue transfers.

the interesting this is it's doing this even without a switch in the middle.

i tried connecting a different NIC to both computers and going NIC -> NIC with no router/switch in between and it stills tends to drop