ramdisk manipulation?

Forum: HD Install
Topic: ramdisk manipulation?
started by: winjimmy

Posted by winjimmy on July 21 2004,00:30

I'm not new to DSL, having used it regularly since the 0.4.x releases. Recently, I decided to try it out on a machine where I wanted to run some OS on an external USB HD (machine has no real HD, but is a thin client type thingy). That turned into a much larger project than I wanted or expected - learning what's involved in booting/running from USB, especially if there's no BIOS support - and involving a few distros. Nothing really does this "out of the box" like I was hoping. And I just can't take all this time out recompiling kernels and assembling initrd's on other machines in order to make this work. So, I'm back at other ways of using DSL that sort of approximate what I want. I'd like some advice from the DSL initiates on this list.

Putting the KNOPPIX folder on USB and booting that way is sort of out: you see, this is a low RAM situation (64MB), and ideally I'd like to have no ramdisk at all. I see no advantage to that means of booting over just booting from CD. Additionally, there's no floppy drive in this thing. And I really don't need anything approaching a full blown distro - even one with as few features as DSL has. I'd be pretty much satisfied with: Xvesa, networking support and a good modern browser (Firefox). All the rest of the DSL stuff is really not needed for this machine.

What I've done thus far is download and install Firefox, then copied the Firefox dir to my external HD. Saved system settings (using backup) to another partition on that same drive. So, the machine is set to boot the CD and get settings from /dev/sda2 (external HD) via initial user input, then mount /dev/sda3 (where Firefox lives) and open the browser on the desktop. This sort of approximates what I'm after. But what I don't like is the fact that this ramdisk is sitting there, largely unused, taking up nearly 3/4 of the machine's limited RAM: I'm looking to get back some of that RAM for the browser that I'll run most of the time.

I suppose there's no simple way to minimize the ramdisk's size at bootup, right? I'm guessing a script hardcoded onto the CD sets this. What I'm thinking might be possible is something like what I've done to get Firebird running from the USB HD: bootlocal.sh has been edited to create a dir under /opt, then mount the USB HD partition there. So, I'm thinking maybe I could move the contents of ramdisk on the fly to the USB HD, do some sort of pivot-root thing to the new ramdisk, then unmount the ramdrive to free up that RAM. Sounds pretty complex, and it might just involve so much kludging that it could cause the computer, and my apartment along with it, to escape earth orbit and never be seen again. Or, more likely, it would be such a fragile balance that the machine would be continuously crashing under normal use.

But anyway, submitted for your consideration. Any of you more advanced hackers have any ideas for how to accomplish what I'm after (i.e., freeing up as much of the ramdisk as possible to convetional RAM for the browser's use utilizing the external HD)?

Thanks, James

Posted by winjimmy on Feb. 03 2006,17:48

Over a year later, it looks like this could'a been accomplished using info I posted to this thread: < http://damnsmalllinux.org/cgi-bin....t=11212 > . That doesn't address unmounting the ramdisk like I asked about in the current thread, but I could have used the same process I used to make the floppy to put files on this machine's tiny IDE flash drive (4MB), which I was booting into a limited FreeDOS from, and then booted to DSL on an external USB drive. Seems like a reasonable way to use the ThinkNIC as something more like a real computer. But the USB drive has to be big enough: no less than 1GB, as I learned from trying to use a 512MB flash drive. Too bad the machine's dead now, or I'd have another go at it.

James