gnupic: Ideas towards small/compact/wear-leveling PIC FlashFS (was: Re: flash filesystem for pic and 24xxx EEPROMs?)
Subject:
Re: Ideas towards small/compact/wear-leveling PIC FlashFS (was:
Re: flashfilesystem for pic and 24xxx EEPROMs?)
From:
"Alex Holden" ####@####.####
Date:
7 Jan 2005 14:43:00 +0000
Message-Id: <49576.82.70.130.130.1105108980.squirrel@www.alexholden.net>
David McNab said:
> In summary, every possible block on the disk would contain a record of
> how many times the block has been written to. If this exceeds the rated
> wear count, the block is marked inactive, and its contents are copied to
> a freshly allocated block.
I think the idea of wear levelling is to spread the writes out as much as
possible so no blocks fail prematurely because they've been written to
much more often than average. Another way of doing a FS on some media
which wears out after too many write cycles might be to do a verify after
every write and stop using any blocks which fail. Your plan is to use one
block until it reaches the manufacturer's 'minimum guaranteed write
cycles' spec and then stop using it even if it still works, which seems a
bit wasteful because the specs are usually very conservative due to the
large number of factors which effect the longevity of a flash cell.
--
------------ Alex Holden - http://www.alexholden.net/ ------------
If it doesn't work, you're not hitting it with a big enough hammer
