Many people have heard of and have used RAM disk images under Linux, but did you know you can do the same thing with Solaris 10? Well, it's a little known fact, but you can, which is great for the potential of using Solaris 10 or OpenSolaris on embedded devices or even on security devices like firewalls.

Here is a quick method (courtesy of Peter Buckingham on one of our internal aliases) on creating a RAM disk image under Solaris 10 x86/x64 or OpenSolaris x86/x64:

1. Install Solaris onto a disk based system
2. Tar it up (except for proc)
3. Modify /boot/solaris/bootenv.rc and remove "bootpath"
4. Modify /lib/svc/method/fs-usr and change mountfs to remount / instead
5. Modify /etc/vfstab and
   - change rootfs to be /devices/ramdisk:a
   - remove swap
   - remove /tmp so it's not swap backed
6. Now use the /boot/solaris/bin/root_archive command to build the RAM disk image:

   eg # /boot/solaris/bin/root_archive pack solaris.img <dir>

   ... where <dir> is the directory you've got your working filesystem in.

Now you have a RAM disk image, there's nothing really stopping you from loading it from the network via pxegrub/pxelinux, or from a local disk.

— Published 17 January 2007