Re: ext2 on flash memory

From: JÃrn Engel
Date: Fri Jun 15 2007 - 12:41:26 EST

On Fri, 15 June 2007 18:16:44 +0200, DervishD wrote:
> Yes, I understand. That's worse than I thought. I was right now
> thinking about "PortableApps", a set of free software applications that
> are a little bit modified to work from a pendrive in Windows. Very
> useful, because you can carry your OpenOffice (or AbiWord) and Firefox,
> for example, to any Windows you're doomed to use. This applications
> write repeteadly to the pendrive (specially Firefox...), and I think
> they may wear the drive prematurely if used extensively.

Possibly, yes. Estimates based on unknown numbers are hard, though.

> So you have a zone which is unusable. Decent filesystems allow you
> to mark some blocks as "dontuse" (ext2, for example). Does FAT allow
> this?

I don't know. If things get bad enough that you experience
uncorrectable errors, I'd just trash the stick and get a new one
instead. Trouble is - with a controller chip doing the error
correction, you have no means of knowing when this happens.

> I think I will be writing the pendrive, almost fully, once a week
> (enough for an image of my home directory). That means less than 1GiB
> written each week. That means 50-100 (in the worst case, making two
> backups a week instead of one) writings each year in each block.

Writing everything once a week is harmless. Filling the whole device is
best-case behaviour. Local hot spots are the problem.


Anything that can go wrong, will.
-- Finagle's Law
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