On Tue, 1 Jul 2014 10:03:44 Rohan McLeod wrote:
Noah O'Donoghue wrote:
Hi All,
After reading about bitrot and feeling guilty for storing my most
valuable data on cheap drives (although with backups!) I've been
thinking about moving to something more resilient.
Out of curiosity I googled "bitrot" and whilst there seems to be some
usage of "bitrot" in relation to RAM;
mostly it seems to be in the context of storage media.
As a novice I found:
http://arstechnica.com/information-technology/2014/01/bitrot-and-atomic-cows
-inside-next-gen-filesystems/
http://en.wikipedia.org/wiki/Write_Anywhere_File_Layout
That article claims that ZFS is the oldest of the "next generation
filesystems". WAFL did it first and NetApp (the developer of WAFL) sued Sun
alleging patent violation in ZFS.
informative; but apart from a suggestion that it
might be related to
'cosmic rays' and thermal magnetic effects;
couldn't seem to find
(a) a definition which is a measure of bitrot and
(b) actual measures of this phenomenon in various media and differing
conditions.
Presumably as a probabilistic phenomenon; bitrot might be defined in
terms of the half-life of the data ?
http://research.cs.wisc.edu/adsl/Publications/corruption-fast08.html
The above paper is the best reference I've seen. Half-life isn't a good
measure as you can expect to lose ~50 sectors at a time on a TB+ disk.
On Tue, 1 Jul 2014 12:29:39 Peter Ross wrote:
For Russell: Have you seen this?
https://wiki.freebsd.org/ZFS
The first TODO entry is about file(1) and magic.
That is about ZFS dump files (the output of "zfs send") not the block devices.
As I have never run zfs send and don't have any immediate plans to do so this
hasn't been a concern for me. Thanks for the suggestion though, I've attached
it to the Debian bug report.
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