An error occurred during send operation SPI across SonicWALL VPN

Using Shadow Protect ImageManager to replicate my backups offsite, I hit a problem.

In short the error I was receiving read like this


ftp://192.168.135.49/Create/Create (SERVER01)

An error occurred during send operation: E_VOL-b001-i1841-cd.spi

This has previously happened (on 1 in every 100 or so compacted daily files) and the only way to resolve the problem is to pause ImageManager replication job and manually FTP or copy via SMB to the remote NAS.

In this particular case, the file was still failing at roughly the same percent way through.

This had me stumped. After doing some tests
- Installing an FTP client on the Management server and connected via FTP to the NAS I hit the same problem. The file in question was about 330MB and it would fail each time at 240MB.
-  Zipped the file up and attempted to FTP across the VPN. Once again the file failed.
- Copied the problem file across the LAN (management server to a desktop PC) without problem. This was successful.

Filezilla is the client used, and the error received. I attempted to resume the file, however it constantly failed.

This then lead me to take a step back from the management server and logged into the clients SonicWALL NSA 240.

I then began watching the logs and started replication again. Sure enough at 240MB the SonicWALL through the error below ( from LAN->VPN )

I then went into Security Services/Gateway Antivirus on the SonicWALL and disabled AV for outbound FTP. I restarted the transfer and the file began replicating past the 240MB point :)

Conclusion: Security and UTM should be at the top of everyone's priorities when configuring a network. The weakest point is usually the first point compromised, however when the hardware and software get what we take for granted wrong, it can be most frustrating. Troubleshoot... Troubleshoot... Troubleshoot.