Question:

How to resolve session hangs and timeouts during FTP directory listings in Vault?

Answer:

If a directory is very large (tens of thousands of files), it takes a long time for the server to retrieve information from the database. If the FTP client timeout is not large enough, the session can timeout during the listing (MLSD/LIST). It usually terminates the session before the file transfer can be initiated. Per the Vault Help, users are instructed to set the timeout to "180 seconds if uploading large files". However, for very large folders this may be insufficient. Increase timeout to at least 300 seconds. 

Steps to adjust timeout in FileZilla:

1. Go to Settings.
2. Click on the Connection page.
3. Go to the Timeout section.
4. Adjust Timeout in Seconds setting.
5. Restart FileZilla.

Timeout values above 350 seconds overlap with inactivity timers on the NLB (Network Load Balancer) which can be resolved with the keepalive settings in the client.  The FTP keep-alive setting sends commands between FileZilla and the FTP server at short intervals. This resets the time-out function and prevents the server from closing the connection. 

Steps to add keepalive in FileZilla: 

1. Go to Settings.
2. Click on the FTP page.
3. Go to FTP keep-alive section.
4. Enable Send FTP keep-alive commands.
5. Restart FileZilla.

Set Host setting to vlt-<PODID>-ftp.veevavault.com in order to avoid the NLB.

Related Documentation:

Vault Help Documentation: Accessing your Vault's File Staging Server