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Re: [vox-tech] Creating large ramdisks
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Re: [vox-tech] Creating large ramdisks

Micah J. Cowan wrote:
On Mon, Feb 20, 2006 at 01:05:16PM -0800, Ken Herron wrote:
John Wojnaroski wrote:

Is there a way to create large ramdisks (around 200meg) that act as a 
single partition?  I seem to recall seeing something on the topic a 
few weeks ago while surfing, but now can't seem to locate the site by 
googling when I need it?
Sure, it's a filesystem type called tmpfs. All of the memory for file 
storage is taken from the system's virtual memory (ie swap space). For 
example, I use this entry in /etc/fstab for my /tmp directory:

    tmpfs           /tmp            tmpfs   size=512m       0       0

Yeah, but if it uses swap, doesn't that sorta defeat the probable
purpose of a ramdisk partition?

I'm pretty sure there's something that will do this, but I don't recall
what it was... 
Right, plus would not swap be mounted on a hard drive, excerpt from RH docs

Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the physical memory is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory.

What I'm hoping to achieve is a diskless workstation, something akin to ltsp but with everything (including all directories, apps, and data) running on the workstation after boot;  embedded it you will;  kind of an iPod on steroids ;-)

Download a small kernel with an initrd ( say 8megs) with PXE or etherboot to a ram partition /dev/ram0 that mounts the kernel and a minimal system that can create a large ramdisk, reset the initrd to a root directory (avoiding any need for pivot_root), then download a bunch of tarfiles from the server, untar the same, and launch applications.  All based on scripts with no operator intervention other than throwing the power switch.  Think I have a handle on everything except how to create the large ram disk.

ATM the workstation downloads and boots to a shell prompt. would like to keep it under 8megs and it looks doable. Then load in all the X-windows stuff, additional shared libraries and apps, and launch
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