Hi Kyle,

On Mon, Feb 13, 2023 at 1:12 PM Kyle Sanderson [off-list ref] wrote:

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The benefit of this can be the data disks are all zoned, and you can
have a fast parity disk and still maintain excellent performance in
the array (limited only by the speed of the disk in question +
parity). Additionally, should 2 disks fail, you've either lost the
parity and data disk, or 2 data disks with the parity and other disks
not lost.

I think I understand the high level idea here. But I think we need a lot more
details on how to implement this, and what the system would look like.
Also, I don't quite follow why the data disks can be zoned devices and
still maintain excellent performance.

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I was reading through the DM and MD code and it looks like everything
may already be there to do this, just needs (significant) stubs to be
added to support this mode (or new code). Snapraid is a friendly (and
respectable) implementation of this. Unraid and Synology SHR compete
in this space, as well as other NAS and enterprise SAN providers.

Assume we figure out all the details. I will be happy to review patches in
MD code. But I won't be able to develop this feature myself.

Thanks,
Song