does anyone know if Mac os has sort of CD like the windows PE which you can use to boot up a computer ? we can use that kind of cd to access the computer's hard drive or do maintainments when the system crashs.
You can use a Linux Live disk to install a Live version (running off the CD) to access the data on the hard disk without using the main operating system.
You can boot off the OS X DVD and do some repair work from there (in particular the disk utility is available). There is a program called BootCD that creates a bootable CD, but it only works with 10.3 and earlier.