Tuesday, December 1, 1998

Take WebDrive out for a spin


By David Gewirtz

Most serious Notes and Domino administrators will understand the concept of a virtual file system. But for those who are still learning, it might be useful to take a few moments for a tutorial.

When you access your local hard drive (the one that's physically installed in your computer), you're pulling chunks of data off the drive. In most operating systems, data is arranged on the drive in files, and organized by directories. This, of course, is how Windows works.

In most programming environments, when a program wants to read in the contents of a file, it first opens the file, telling the OS that it's intending to use that file and asking the OS to make it available. Then the program will retrieve chunks of data from the file. In the simplest case, the data is returned to the program in sequential chunks, one right after the other. When the file is read, the program then closes the file.

Because these file access calls (and a whole pile more) are built into the operating system, most programs that access files on disk access them through the operating system file I/O calls. So, when you're in Word for example, and you select Open from the File menu, you see a list of files sitting on one of your local (i.e., on your own computer's) hard drive.

But, as many of you know, you can also access files from your server. If you're running NetWare or NT, for example, you can "mount" a remote hard drive's file system to your local file structure and access it as though it were just another file on your computer. The file system that's on the remote system is considered by all the higher-level applications to be local. The remote file system is "virtually" part of the local system.