Re: Sid and Root on Compact Flash ?
On Mon, 5 Apr 2004, Iain Young wrote:
> Hi All,
>
> I've seen a number of 'HOWTO' documents on installing Debian on
> Compact Flash, but most of the ones I've seen deal with installing
> it once, and using stable.
>
> Has anyone had any experience with using Sid, -and- keeping it
> up to date with apt-get update and apt-get upgrade regularly ?
>
> How long do the modern CF cards last before they need to be replaced ?
> Most of these machines would be router || dns || ldap type machines -
> ie small, dedicated for a particular job, rather than general purpose,
> or graphics.
>
> Any other tips ? I guess moving syslog to be over the network
> might help, but I'd think the apt-getting would probably be more
> costly in terms of CF life.
>
> I'm thinking of migrating my home machines to the Mini-ITX factor,
> and so was considering going all the way, and doing without a hard
> drive in most cases.
>
> (And yes, Im one of those nutters who like to have the leading
> edge software)
>
AFAIK, this technique is mainly used for "embedded" systems and I put the
quotes there because one man's embedded system is another man's Cray. The
CF disk normally would contain a kernel image, a compressed root
filesystem, and a bootloader like 'syslinux' (on a i386-based system)
that loads the kernel, then loads the filesystem image and then boots the
kernel. The kernel is configured to have its root filesystem loaded as a
ramdisk. The CF disk has a FAT 16 filesystem on it and is normally not
mounted at all during operation. It can be mounted periodically to
read/write configuration files that can be used to configure applications
in the root filesystem (in the ramdisk).
The advantages to this are that the filesystem image is virtually
incorruptible and there is no harddisk to fail. Embedded systems are
typically not "shutdown" nicely like a desktop or server, but are just
switched off.
This is very practical for "appliances" like you mention, but I would
think impractical for a general-purpose desktop or server. I do not think
that it is practical to maintain such a system as a Debian machine because
the filesystem image that I have described must be "built" using a bunch
of tools.
My day job is developing routers and network communications devices for
military applications and we've been using Linux in an embedded sense
since about 1999. We did release an early product that was essentially a
Debian filesystem (with a lot of stuff ripped out of it), but it was
significantly larger in size than one can do by building one's own
filesystem and is not really the way to go.
I don't know what your background or desire is in terms of doing this, but
my feeling is that one really needs to do some software development to
build something like this. There are a lot of resources on the web about
this, search for "embedded linux". There is also a great book on the
subject, "Building Embedded Linux Systems", by Karim Yaghmour, that I
highly recommend.
There was a very interesting and useful project called the Linux Router
Project that unfortunately is now dead, don't know about any spinoffs from
it. This provided somewhat of a turnkey system like what you are
describing.
There is something called PTXdist <http://www.pengutronix.de> that is a
developer's tool to provide a significant jumpstart to developing an
embedded Linux system that you might check out.
There is a Debian-related project called Emdebian
<http://www.emdebian.org> also.
Anyway, there is a TON of stuff on the web about embedded Linux and a lot
of embedded distributions in various states. You'll need to do a little
research and see what you can find that fits your application and interest
level.
Good luck...
Reply to: