Tried to ferret out the answer to this myself and so far so bad.
This just 'popped in there' while I was optimizing something completely
different... in a RAID-1, writes have to be mirrored of course, thats
what RAID-1 is, but for reads, could they not be sped up by a
significant amount if a storage pattern was chosen such that large
blocks of data were "striped" in an in-order/out-of-order scheme? In
other words, store all the data on both drives, but in huge (2x cache
size) -ish blocks that might allow 50% of a given [large] access to come
from each drive, with trivial [smaller] reads always coming from one or
the other chosen at random.
Downside, I know, is that the data would be organized ina way only the
raid subsystem would understand, so the niceness of pulling a mirrored
drive out of service and it being a literal copy of the otehr drive
would be lost, but for such a speedup I'd be willing to pay the price of
always having to access it as a failed set (worst case) through the
md-daemon.
Am I off into the weeds?
-Curt
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