Re: [Gluster-devel] ECC translator

[Kevan Benson]

Csibra Gergo wrote:
> Hi,
>
> My name is Gergo Csibra, and I live in Hungary.
> I'm new to GlusterFS, but not new to Clustering/HPC and programming,
> I'm in GUG project (http://sourceforge.net/projects/gug)
>
> So, I want to make an ECC translator, with this we can make a raid
> like bricks. I think this very close to encryprion translators,
> because this does the same thing:
>
> reads data from client
> manipulate this data
> writes to subvolume
>
> an reverse:
>
> reads from subvolume
> manipulate (really only checks, and maybe repair) readed data
> sends to client.
>
> I've looked the rot-13 translator, and after 2 days of
> missconfiguration I can test it.
>
> My questions:
> The encryption translator reads and writes same amount of data, but I
> must write more data to device (the original plus the ECC info), and
> send less to the client (readed minus the ECC).

Actually, you probably just want to write and read the same amount, let 
the portion that does the ECC (or RAID-5, as that's really what you are 
implementing at this point) take care of everything.

> The other thing, if I make for example 4 ECC bytes to every 16 user
> bytes, maybe I need to read data from before and after the original
> buffer.

You would probably be better off working with the striping translator, 
as what you really want is striping + parity (You can do it with a 
designated parity volume, but it kills performance, it is much easier to 
implement though).

> What functions must I use, to do this thing?
> Is there some development documentation?
>
> ps. sorry for my english :)

Don't know much about dev docs.  Maybe someone else can help you.

--

-Kevan Benson
-A-1 Networks