Backup Jobs Error NFS + Rsync (2 x Pro Pioneer)

[jck_co_im]

Hi, have 2 Pro Pioneers in same Building on gigabit LAN. I had about 6 Rsync jobs setup which used to work fine. In the past month they've been consistently failing.

I cant make a successful Rsync or NFS job (NAS < > NAS) happen from either of the Pro Pioneers (via schedule or from Front View manually).
(Unless the folder is empty, or contains a small number of files, or the files are duplicated manually via drag and drop.)

I've found that CIFS backup via Frontview still works (between both devices, bit slower than Rsync)
Users have no issues accessing the device on the LAN, copying files to and from it with XP or Win7.
"Test Connection" says "Successful" when setting up a backup job.
Network interface info. not showing any errors.
Ralus Backup Exec works fine backing up to srvr2k8 tape drive(installed on one of the NAS units)
No file corruption has been encounted.
Write Cache is off on both units.(raid6, 6 x 500gb)


Here is the Rysync Error I get with all backups; or the Rsync job freezes altogether running for hours/days

Backup failed. Thu Jul 21 17:55:14 WEST 2011.

Reason for failure:
Error encountered copying data from remote source path 192.1.2.145::**** ==> /****/ due to unknown reason. Please see log.
(although there is nothing in the log)

Here is the NFS Errror.

Job: 007
Protocol: nfs
Source: 192.1.2.145:/********
Destination: [*******]/


cp: cannot access '/job_007/.': Input/output error
cp: '/job_007/.': Input/output error

So far I have;
disaled add-ons (FTP Who, Media Streaming)
Reset all permissions in folderson both units (including NFS, Rysnc to public Read/Write)
Toggled services on and off.
AFP Disabled.
Removed unused Readynas Remote add-on.
Reset second Nas to factory default + restored folders and settings from cfg backup.
Upgraded second Nas to 4.2.18 after (other unit still on 4.2.17)

Using SuperPoussin's NasMonitor, the Rsync service is running in 2 threads, shows connected via IP address, but moves no data, consumes no/little CPU resource.
NFSD is running in 4 threads, this behaves much the same, consumes little/no resources.
(Same on both Pro Pioneers)

I'm a bit of a loss, I can't see what else could restrict Rsync or NFS

[ewok]

If you have jumbo frames on, try turning them off.

[jck_co_im]

Thanks, I'll try it on monday

[jck_co_im]

The disabling of jumbo frames did the trick.
I'm guessing there must be an issue with one of the switches or cabling, if it worked a few months ago?
Thanks again