-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sun, Jun 03, 2007 at 11:00:27AM -0300, Gerhard Fiedler wrote: > Sean Breheny wrote: > > > Has anyone addressed the problem of max number of writes, though? > > Yes. Windows XPe: > . I've also seen > distros for Linux that offer solutions for this; just don't have any links > handy. On Linux you have a lot of options for avoiding writes to disk. It's quite easy to disable swap entierly, you can also set swap to be only used if you have truely run out of memory rather than the usual swap stuff out to have more cache ram. You can also move stuff like log files into ramdisks very easilly. They would be deleted on power down, but for an embedded application this may be appropriate. You can even set the disk caching mechanism to practically never flush writes to disk. Originally this feature was developed to extend the battery life on laptops, but it'd be appropriate for flash as well. Finally you can use the money you saved on software licenses to just buy a harddrive. > Correct, but with suitable caching, I don't think that any of this is > noticeable unless you're really needing high throughput writes. Harddisk > head positioning is also not instantaneous, and just as you need to write a > whole block if you want to write 10 bytes, you need to move the head to the > target location even if you only want to write 10 bytes. I didn't test it, > but I'd say for writing 10 bytes, a typical Flash is way faster than a > typical harddisk on average. Only if you need to flush the write to flash immediately. I can't speak for other OSes, but on Linux many of the filesystems have very advanced write re-ordering code. So if you make 1000 tiny changes scattered around the disk, the changes aren't flushed to disk immediately but instead linux saves them in the cache until enough adjacent writes are accumulated to make it worth a write to disk. Of course for high-integrity stuff, like databases where you must have transactions immediately written to disk, and in particular orders to satisfy transaction constraints, then yes flash is a huge win and indeed there are already many flash or battery-backed ram based cache layers available for those applications. - -- http://petertodd.ca -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGY1Yp3bMhDbI9xWQRAlvaAJ9Ov3JJvPErdbRpVuSHEY9WgFcYsgCfTtqO gyO/UODrtB2/CQIj7/BsRLY= =JFR5 -----END PGP SIGNATURE----- -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist