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Re: [ts-7000] Re: Help creating Debian on CF!!!

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Subject: Re: [ts-7000] Re: Help creating Debian on CF!!!
From: Jim Jackson <>
Date: Sun, 4 Sep 2005 22:17:28 +0100 (BST)


On Sun, 4 Sep 2005, ld_ts7200 wrote:

> Is the RAM drive used to run programs from?

Yes it can - but I think you are not understanding.

You can run programs from the CFdisk when mounted as
read only. By mounting readonly it cannot be corrupted, hence if power is
lost there is no problem.

But because the CFdisk is mounted readonly, you need to have somewhere
where data can be written. Hence you can use a filesystem on a ramdisk

>
> Are there any restrictions on using the RAM drive?

Any data on the ram disk is lost when power is lost, or when the system is
rebooted. You only have 32M of memory, removing 4M for a Ramdisk only
leaves you with 28M of RAM and NO SWAP. So watch what applications you
expect to run!

Elsewhere JFFS is mentioned, presumably because it a Jouranlling flash
file system - and journalling helps survive unclean reboots, power losss
etc. I'd check JFFS stuff, but I think the CFDisk interface to the falsh
is good enough to support JFFS ???? I may be wrong.

You could put an ext3 FS on the CFDisk - but ext3 does 3 writes for every
1 write on an ext2 FS (write change to journal, do the actual write, erase
change from journal) so you can wear out the flash quicker.


There are other approaches to this problem. Given the low power
consumption, having a battery backup supply and detecting when
main power goes and shutting down cleanly is fairly easy - along with a
software poweroff switch to shutdown completely after everything is clean.




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