NetWare high utilization while downloading files via FTP (NWFTPD.NLM)

  • 7002810
  • 24-Mar-2009
  • 26-Apr-2012

Environment

Novell NetWare 6.5 Support Pack 5
Novell NetWare 6.5 Support Pack 6
Novell NetWare 6.5 Support Pack 7
Novell NetWare 6.5 Support Pack 8

Situation

NetWare 6.5 SP5 or above may experience periods of high utilization while files are downloaded to an FTP client, via NWFTPD.NLM.

Resolution

The high utilization during FTP download is linked to the new "TRANSMITFILE_SUPPORT" feature added in to FTP Server in NetWare 6.5 SP5.  This parameter is found in SYS:ETC\FTPSERV.CFG, or in iManager --> File Protocols --> FTP (NetWare) --> Select Server --> Select FTP Instance --> General.
 
When this parameter is set to "YES" (or when the check box is enabled), NWFTPD uses newer methods of transmitting files, which may, in certain environments, allow faster downloads.  However, while this feature is in use, the server utilization will jump much higher than it would if this feature was set to "NO".
 
The high utilization is not a fatal condition, and will pass once the download is completed.  However, it could slow down other processes running on the same server.  Furthermore, testing has shown that many environments do not get significant download speed benefit from the TRANSMITFILE_SUPPORT feature, so use of this feature is not always an efficient trade off.
 
If use of this feature is desired, Novell recommends careful testing and observation to determine whether a significant download speed benefit is actually obtained during normal production loads and conditions, and whether the utilization trade off is acceptable.  Even if no speed improvement is seen, a utilization sacrifice will occur.
 
In general, Novell expects most environments will perform best with TRANSMITFILE_SUPPORT=NO.
 
Note that the new transmission method is only in effect for files *downloaded* from the FTP Server's own local volumes.  It is not in effect for uploads, nor for downloads which come from a remote server's volumes, through NWFTPD's ability to use server-to-server NCP connections.

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