HOWTO: Create a Solaris 10 RAM Disk Image

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.