rsyncing files in flash

[Bennett Todd]

2003-02-25T11:25:29 wim delvaux:
> I wonder how rsync works when files-to-be-updated are in flash
> (e.g. on IPAQ)

Same thing that happens anywhere, as long as the flash is presented
as a filesystem with POSIX semantics to a platform where rsync can
run. I use rsync for automatic backups of Memory Stick flash cards
routinely.

> Ideally rsync should write to the flash as little as possible
> (because of max reflash count)

To the best of my knowlege, that was a quite minor issue with the
first generation of flash media, and has since been engineered
entirely out of existence, with a combination of newer flash media
enjoying far greater numbers of permitted write cycles, and
low-level hardware controllers automatically cycling blocks about to
spread out hot spots. I'm pretty sure limited-number-of-writes is
no longer expected to limit the life of flash media in practice;
it'll keep working until it's so obsolete that you throw it away. My
old 10MB PCMCIA Type II Flash card isn't very interesting with all
my devices supporting the (far cheaper and smaller) 128MB memory
sticks, for instance.

> If file needs to be updated, the new file is created.
> Then the old file is deleted
> the new file is renamed to the old file (making sure that the file does not 
> get copied over)
> 
> Is this what happens ?

That's in fact exactly how rsync behaves, congrats!

-Bennett
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