DataSync Task unavailable : mount.nfs: access denied by server while mounting

Question

I am consistently unable to start a Datasync task to transfer from a local NAS (Synology) to s3.

Tried dozen of times with slight changes, NFS versions, squash options, agent reboot, etc... with no success.

The tasks all have the unavailable status, with an error message "mount.nfs: access denied by server while mounting..."

Setup:
- DataSync agent running as a KVM VM on ubuntu 20.04 LTS
- DataSync agent connected
- NFS share on a Synology NAS on the local network
- NFS share permissions provided for the agent IP (and even for the local network)
- DataSync agent connectivity and NFS connectivity tests are all successful
- mounting the NFS share on ubuntu 20.04 LTS works perfectly

Could you please help? What is going on?

Answer

DataSync mounts NFS servers as the root user (UID and GID = 0).  It is recommended to enable no_root_squash on your NFS server to avoid permission issues.  Relevant links:
* https://docs.aws.amazon.com/datasync/latest/userguide/create-nfs-location.html
* https://docs.aws.amazon.com/datasync/latest/userguide/troubleshooting-datasync.html#onpremise-location-stuck-mounting

Answer

SOLVED!
FYI the issue was a combination of factors in the NFS share permissions, this config finally worked:
- you have to allow the DataSync agent host IP, not the agent VM IP
- non privileged ports (>1024) are necessary for the DataSync agent (although not necessary for ubuntu clients)
- Squash : no mapping
- Synology NAS NFS permissions behave strangely if there are IP overlaps accross permissions, avoid overlaps

Answer

Hi there,
I am trying the same scenario. Thanks for the configuration tips on Synology DSM. But I am still missing something.

Still getting the error "mount.nfs: access denied by server while mounting"

Please, any other relevant configuration on DSM or DataSync Agent to access the mounted shared folder in Synology?

DataSync Task unavailable : mount.nfs: access denied by server while mounting

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