Backup randomly fails on Synology NAS

M

mirmalag

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Proxmox Subscriber
Dec 26, 2021
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I have troubles backing up an LXC container on PROXMOX VE 9.
I do it as a backup job that saves shapshot images on a NAS.
Strange thing is that it happens sometimes, not always.

Traced error is:
2026-01-10 01:05:02 INFO: zstd: error 70 : Write error : cannot write block : Bad address

Backup NAS is a Synology RS422+ (OS DSM 7.3.2)
Images are saved on a mounted folder shared by the NAS as an SMB volume
Diagnostics on the NAS did not reveal any problem.

More detailed infos are attached.

Can you please help to understand?
 

Attachments

Hi,
not entirely sure if noserverino also helps in your cause, but I'd give it a try:
P

[SOLVED] Thread 'SMB/CIFS mount point stale file handle'

Hi all,

i have a SMB/CIFS MP bound into proxmox and used in the vms/lxc.
In the past week the mount seems to went bad as it return stale file when used on the lxc and even in proxmox itself when i try to cp a file for example.

I unmounted by umount --lazy and removed the dir from /mnt/pve/<share> and set it up again. Error still exists. So i removed the mp from all vm and LXC and removed again from proxmox and set it up again (using cli pvesm add cifs... and webinterface).

if i check with command df i see it succesfully mounted on the path.

Any ideas will be appreciated.
Thanks.
 
fl0moto said:
Hi,
not entirely sure if noserverino also helps in your cause, but I'd give it a try:
P

[SOLVED] Thread 'SMB/CIFS mount point stale file handle'

Hi all,

i have a SMB/CIFS MP bound into proxmox and used in the vms/lxc.
In the past week the mount seems to went bad as it return stale file when used on the lxc and even in proxmox itself when i try to cp a file for example.

I unmounted by umount --lazy and removed the dir from /mnt/pve/<share> and set it up again. Error still exists. So i removed the mp from all vm and LXC and removed again from proxmox and set it up again (using cli pvesm add cifs... and webinterface).

if i check with command df i see it succesfully mounted on the path.

Any ideas will be appreciated.
Thanks.
Click to expand...
Hi fl0moto. I will investigate it but think is not the same problem.
mount's man page says noserverino option has to do with how to treat hardlinks, which are not present among the files I backup.
Thank you anyway.
 
Hi Mirco,
the backup jobs are executed by the pvescheduler (usually run as systemd service).

So for debugging you can try to stop the systemd service and start the scheduler with a strace (and maybe in debug mode). This will generate a lot of output, depending on the others scheduling jobs.

BR, Lucas
 
Hello,

Have you found a fix for your problem ?

I have the exact same problem.

I have a node with 21 VM running on it.
The backup is done daily with the integrated backup system vzdump.
Most of the time it fails randomly on 1 or 2 VMs, always different VM, different time, different place.

105: 2026-03-22 21:13:36 INFO: 52% (130.1 GiB of 250.0 GiB) in 3m 55s, read: 0 B/s, write: 0 B/s
105: 2026-03-22 21:13:36 ERROR: vma_queue_write: write error - Broken pipe
105: 2026-03-22 21:13:36 INFO: aborting backup job
105: 2026-03-22 21:13:36 INFO: resuming VM again
105: 2026-03-22 21:13:37 ERROR: Backup of VM 105 failed - vma_queue_write: write error - Broken pipe

I sometimes also gets the "INFO: zstd: error 70 : Write error : cannot write block : Bad address" message.

I'm running PVE 9.1.6 and the storage is a mounted SMB share hosted on a Synology.

Anyone facing that issue and that might have a solution ?

Thanks
Mike
 
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