/proc and Software RAID
The /proc filesystem is a virtual filesystem that provides information about the system and the running kernel. Files located in /proc provide vital information about memory, devices, and processes. Here is also where you look for current information on active RAID devices. Virtual files under /proc provide information in real time. By default, the kernel is configured to support the /proc filesystem. However, to be certain that your kernel supports /proc, look for its entry in the File systems subsection of the kernel configuration:
File systems ---> ... [*] /proc file system support ...
Files located in /proc are usually displayed using the cat command, but you can use any program in which you can view a text file. Most of the files in /proc merely provide information (they are read-only), but some actually offer the means to manipulate the way a running kernel operates. In that case, administrators usually write new values to a file using the echo command.