ERROR: 503 Service Unavailable in iManager >'File Protocols'>'FTP'

The HTTP error "503 Service Unavailable" is returned when attempting to manage a remote NetWare FTP server across a slow link with iManager >'File Protocols'>'FTP'.

When you manage a NetWare FTP server with iManager, the FTP plugin module for iManager will access some files, like configuration files, over NCP on the NetWare server that hosts the NetWare FTP server. The FTP plugin module establishes a new NCP connection and authenticates the administering user for each file to be accessed and it reads the files SYS:\ETC\HOSTNAME and SYS:\ETC\FTPSERV.CFG byte for byte. Establishing an NCP connection and authenticating the user are quite expensive operations and reading files byte for byte generates much overhead and has a significant impact on performance over slow network links. In the bug report, I suggested to change the FTP plugin module so that it will access all files on the remote FTP server over the same NCP connection and hence authenticate the administering user only once and read files in blocks of 4096 bytes (NSS block size) or in total instead of byte for byte.