mendelsohn@frodo.mgh.harvard.edu (Andrew Mendelsohn) (02/14/91)
Has anyone tried me to create a RAM disk from a file instead of a
partition?
To save a partition, it seems possible to make a disk image with
dd and then access it as a device. However, I am not sure how to
create a device that would be essentially a dummy, but point to the disk
image. Any advice?
andy mendelsohn
mendelsohn@frodo.mgh.harvard.eduwjb%cogsci.COG.JHU.EDU@vm1.nodak.edu (02/14/91)
>Has anyone tried me to create a RAM disk from a file instead of a >partition? > To save a partition, it seems possible to make a disk image with >dd and then access it as a device. However, I am not sure how to >create a device that would be essentially a dummy, but point to the disk >image. Any advice? Hmmm, that's an interesting thought. I've thought about loading a RAMdisk with utilities programs, but didn't like the idea of tar'ing a bunch of files over to it. You can do what you want without making any major changes to the system at all. I'm assuming that we are talking about IBM-PC Minix here. First get a copy of the shoelace package, it lets you do lots of things, one of which is specifying the size of your RAMdisk in a configuration file even if nothing is loaded into it. Then in your /etc/rc file do a "dd < diskfile > /dev/ram" and then mount /dev/ram. Before shutting down your system unmount /dev/ram and do the reverse "dd" command ("dd < /dev/ram > diskfile"). I have a "shutdown" script to unmount stuff anyway so adding this would be easy. All of this assumes that you have a filesystem image as a file on your system. To start everything out, you would mkfs /dev/ram, mount it and copy the files you want over to it. All of this is standard Minix except for using "shoelace" to set the size of the RAMdisk. I would guess that the changes needed to set the RAMdisk size to some constant on non IBM-PC versions of Minix should be fairly simple. Good Luck, Bill Bogstad