On Tue, Jan 01, 2013 at 05:15:14PM -0800, JIA Pei wrote: > > But, what do you mean by *(e.g. leaving the system, and reloading it) *? > do you mean *load and remove a module* ? > No, I meant shutting down the system. Or unmounting the card where you are building LFS. > > BTW, why those USB flash or SD card are not intended for long-term use? > What is the trend then? Currently, all popular boards Pandaboard, > Beagleboard, RPI, are all using SD card for booting..... Can you help to > explain why you said that? >
Solid-state storage has a finite number of read/write cycles. If the filesystem is designed for solid-state storage it will work around this. A regular filesystem such as ext4 or xfs will cause a lot of extra writes. Embedded boards use these cards because they are small and cheap - for development, I guess it is a simple matter to replace the card if it wears out. For deployed embedded linux systems you can set them up so that things which write to "disk" write to memory in a tmpfs - perhaps without saving it on shutdown. 'Live' distros for use on usb sticks will use these techniques. So, for a simple system, such as a firewall, I think you can expect reasonable life - provided you do not log to the "disk", and do not compile on it. If I was trying this I would develop on a real disk, then copy that system to a card once it appeared to work. But _building_ a system from source is different - an enormous number of files are extracted from tarballs, compiled to object files, then linked to new executables and libraries. This is what uses up the erase cycles of the solid-state storage. ĸen -- das eine Mal als Tragödie, das andere Mal als Farce -- http://linuxfromscratch.org/mailman/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/lfs/faq.html Unsubscribe: See the above information page
