On Mon, 2005-03-07 at 14:31 -0800, Florin Andrei wrote: > Why Flash? The OS must survive power crashes and other nasty events > without ever failing. I would recommend that you don't use Compact Flash. Most Compact Flash cards just aren't that reliable. Do some powerfail testing -- automatically cut power to a live system very few minutes for a week or two. See what happens. > Q1: Do you think it's too crazy a project to fly? :-) No, plenty of people do it -- just not with CF :) > Q2: > Ideally, /etc should be on the Flash, along with other config-specific > directories. Flash has a problem with being written too often, but all > configs must stay on the Flash for reasons mentioned above. > Actual question: which directories would you put on the Flash in such a > situation? (besides /etc) > Also, /etc has some files which are written to quite often. How would > you get rid of those? Take a look at the Familiar distribution for ideas on this (http://familiar.handhelds.org/). They handle it by using symlinks into a ramfs /var as appropriate, and untarring the initial contents of that ramfs in a /linuxrc script. > Q3: Are there any filesystems that are better for Flash, in that they > "spread" the writes across multiple blocks? > Ext3 and any other journalised FSs should be avoided, right? (due to > concentrating lots of writes in the journal) For CF or other devices which don't really appear as flash but instead pretend to be a block device, there's not a lot you can use which makes much sense. For _real_ flash you'd use JFFS2. -- dwmw2
