[ale] Non-ramdisk based flash filesystem?

[Christopher Fowler]

On Tue, 2006-09-19 at 15:27 -0400, Chris Woodfield wrote:
> The situation: my firewall for the past few years has been a truly  
> ancient Mini-ITX PC with an even more ancient hard drive running a  
> low-overhead Linux install (iptables, ssh, not much else). The hard  
> drive in particular is sorely in need of an upgrade - it's about 8  
> years old and I have no idea how much more time it's got.
> 
> What I'd like to do is eliminate moving parts from this box entirely,  
> and replace the drive with CF or USB flash-based storage. Given the  
> write-cycle limitations of flash, every solution that's come up in my  
> Googling on this subject gives me a ramdisk-based solution where the  
> flash contains a filesystem image which is loaded as a ramdisk, not a  
> live filesystem. The issue here is that the image must be "rebuilt"  
> every time I make a change, such as updating an iptables rule, or apt- 
> get update, compile a new kernel, yadda yadda.

DOM.  Go find yourself a 64mb or 128mb DOM.  Place that in the HDD
connector on MB and make suer they give you a power cable.  A DOM can be
powered by pin 20 on the MB but not all MBs power pin 20.

> 
> What I'd prefer is a system by which I can mount the core filesystems  
> read-only (which I can remount rw when I need to update files, while  
> the more dynamic filesystems (e.g. /tmp, /var) are ramdisks, with the  
> understanding that persistence between reboots is not possible with  
> those partitions.

1. ext2 on the root
2. tmpfs for all R/W sections
3.  Join them with unionfs

> 
> The big question here is, what filesystems in a running Linux system  
> can be mounted RO without causing issues? Of the filesystems that  
> need to be RW, are there any that must be persistent between reboots?  
> What other potential issues could I be looking at with this solution  
> that could make an image-based solution more appealing in practice?
> 

ext2 can be mounted ro.  Nothing needs to be persistent other than your
config stuff.  Like rules.


> TIA,
> 
> -Chris
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