Am 17.05.2012 23:02, schrieb Dan Williams:
I'll have to leave for for hpa to answer. I've occasionally thought that
maybe it should be fixed, but it never seemed worth the effort.
The math assumes 2 data disks.
Aside from a BUG_ON in async_raid6_datap_recov, it seems like it should
work based on a cursory glance. Especially the various gen_syndrome
implementations and raid6_datap_recov look like they should produce the
correct result.
Yes, not possible at present.
It might be as simple and finding the places that impose the limit and delete
them...
You'd certainly need to route around the acceleration code, because
that increased the dependency on the assumption that there is always
two data disk slots.
This, however, makes it seem like lots of hassle for very little gain,
given that the same on-disk data can much more cheaply be produced by
using a RAID1. I think the more sensible thing to do is to add support
for reshaping a RAID1 into a 4-disk RAID6. This should hopefully not be
too different from the existing RAID5-RAID6 reshape, and is probably
what I'll (at least try to) implement when the time comes to expand my
array.
Oliver
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