If you want to create a RAM disk, you can use the command ramdiskadm. The synopsis as the following: /usr/sbin/ramdiskadm -a name size [g | m | k | b] /usr/sbin/ramdiskadm -d name /usr/sbin/ramdiskadm The sample as the following: # ramdiskadm -a disk_a 128m /dev/ramdisk/disk_a # ls -l /dev/ramdisk/ total 1 lrwxrwxrwx 1 root root 40 2010-01-06 20:42 disk_a -> ../../devices/pseudo/ramdisk@1024:disk_a # ls -al /dev/rramdisk/ total 1 lrwxrwxrwx 1 root root 44 2010-01-06 20:42 disk_a -> ../../devices/pseudo/ramdisk@1024:disk_a,raw # newfs /dev/rramdisk/disk_a newfs: construct a new file system /dev/rramdisk/disk_a: (y/n)? y /dev/rramdisk/disk_a: 262036 sectors in 436 cylinders of 1 tracks, 601 sectors 127.9MB in 28 cyl groups (16 c/g, 4.70MB/g, 2240 i/g) super-block backups (for fsck -F ufs -o b=#) at: 32, 9648, 19264, 28880, 38496, 48112, 57728, 67344, 76960, 86576, 173120, 182736, 192352, 201968, 211584, 221200, 230816, 240432, 2500