On 01/02/13 13:05, Ken Moffat wrote: > 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 Going off topic... I was surprised to see the offical Raspberry Pi Linuxdistribution Raspbian installs a swapfile on an SD-card. Not a good idea I think.
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