[lug] Max ramdisk size?

[Jonathan Briggs]

Wow, I learn something new every day!  I didn't know you could define
the size on the kernel boot line.

I really doubt that a single 15 GB ramdisk will work, because I just
looked into the 2.4.19 kernel code in drivers/block/rd.c, and it doesn't
look like the developers planned for anything but 32 bit offsets.

I could be wrong...

I think a better place to ask would be the linux-kernel mailing list.

On Tue, 2002-08-06 at 17:29, Rob Riggs wrote:
> Thanks Jonathan, but all I really want to know is what the limit on 
> ramdisk size is. I do know how to configure large ramdisks. I just don't 
> have a box with 16GB of memory right now to determine whether I can make 
> a single 15GB ramdisk.
> 
> The default ramdisk size can be configured during kernel config time, 
> but I prefer to use the "ramdisk_size" boot option. If I have to resort 
> to building my own kernel (shudder), I'll make the ramdisk a module and 
> use the "rd" module options to set the ramdisk size.
> 
> tmpfs is an option, but since I want all of the data pinned in memory 
> and *never* want it swapped, ramdisk is the preferred option. (In fact, 
> I'd rather crash the box due to OOM condition than swap the data.)
> 
> Thanks again.
> 
> -Rob
> 
> Jonathan Briggs wrote:
> 
> >The ramdisks are fixed in size.  That size can be configured when you
> >build the kernel.  It defaults to 4 MB.
> >
> >I would recommend using the tmpfs filesystem.  It stores files in memory
> >and they can be swapped to disk if needed.  The size can be configured
> >with a mount parameter.  It defaults to half your memory.  tmpfs doesn't
> >immediately use all the memory allocated to it, that's just its maximum
> >size.
> >
> >On Mon, 2002-08-05 at 17:01, Rob Riggs wrote:
> >  
> >
> >>Anyone know what the limit on ramdisk size is? If I have a 16GB (ia32) 
> >>box, can I make a single 15GB ramdisk, or will I need to make a number 
> >>of smaller ones?
> >>    
> >>
> >
> >  
> >
> 
> 
> 
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-- 
Jonathan Briggs
jbriggs at esoft.com
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