On 20/11/13 19:34, Andrea Mazzoleni wrote:

Hi David,

quoted

quoted

The choice of ZFS to use powers of 4 was likely not optimal,
because to multiply by 4, it has to do two multiplications by 2.

I can agree with that.  I didn't copy ZFS's choice here

David, it was not my intention to suggest that you copied from ZFS.
Sorry to have expressed myself badly. I just mentioned ZFS because it's
an implementation that I know uses powers of 4 to generate triple
parity, and I saw in the code that it's implemented with two multiplication
by 2.

Andrea, I didn't take your comment as an accusation of any kind - there
is no need for any kind of apology!  It was was merely a statement of
fact - I picked powers of 4 as an obvious extension of the powers of 2
in raid6, and found it worked well.

And of course, in the open source world, copying of code and ideas is a
good thing - there is no point in re-inventing the wheel unless we can
invent a better one.  Really, I /should/ have read the ZFS
implementation and copied it!

mvh.,

David