I am going to reformat a CentOS server into Ubuntu server.. When I checked the devices available using df -kh command, a 'tmps' with 251MB size, mounted on /dev/shm appeared together with the /dev/sda and /dev/sdb... I know that /dev/sda and /dev/sdb are the hard disks connected, how about this 'temfs', is it also a hard disk?? I don't really get it..please explain. Thanks!