[vox-tech] Creating large ramdisks

[John Wojnaroski]

Ahh, now I see what tmpfs is, perhaps calling it a swap space was a bit 
confusing
See http://www-128.ibm.com/developerworks/library/l-fs3.html

That will work, in fact the article is very informative.  So if I 
understand what you all are saying and the article; a diskless 
workstation or any PC for that matter can use RAM memory as a VFS and 
since the apps will be fixed in size for executable binary and data the 
amount of memory required will be determinate until one begins to 
experience "requirements creep" ;-).

Thanks again for the quick response

JW

John Wojnaroski wrote:

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