For many of you, most likely the majority of you, are using IBM i’s NetServer facility “server side” to present directories in your system’s Integrated File System (IFS) to clients on your network as normal network file shares using the SMB protocol standard. If you are using NetServer in this manner, you are also probably using the “client side” of NetServer called “QNTC” where your IBM i acts as an SMB “client” and reads/updates file shares on your network that are hosted by other servers (other IBM i systems, Windows servers, etc.).
Many shops use the QNTC functionality of NetServer as a nice easy way to get files to or get files from Windows servers in their environment, and the purpose of this article is to make you aware of some little-known system environment variables that control some basic fundamental behavior of QNTC on your system.
To determine what system-level environment variables that you have defined in your IBM i environment, simply enter the command WRKENVVAR *SYS on any command line and the screen below will appear showing all your system-level variables that you have (if any). System variables (e.g. WRKENVVAR) are very much like system values (e.g. WRKSYSVAL) in that they provide a “switch” of sorts to allow you to control all kinds of system behavior, here we will focus on system variables related to QNTC behavior.
Prior to version V5R4 of IBM i, the default QNTC functionality on your system would search for all SMB files shares on your network and only present them to your system if each file server that it discovered was accessible via TCP/IP. This would ensure that QNTC presented to the system a list of only shares that are accessible, but this accessibility “pre-check” caused a performance penalty whenever you tried to access the QNTC file system from IBM i (e.g. WRKLNK ‘/QNTC’ command).
To speed things up, IBM changed the QNTC default behavior as of V5R4 to not perform this accessibility pre-check and as a result, QNTC may present to you shares that cannot be accessed and this could be confusing in network environments where you have many file shares and this QNTC accessibility pre-check is helpful in automatically weeding through which SMB shares are accessible from your system. If you want to re-enable this accessibility pre-check, simply add the environment level variable QZLC_SERVERLIST and set it to a value of