Hi,
> My goal is 4 OSD's, each on separate machines, with 1 drive in each for a start, but I want to see performance of at least the same order of magnitude as the theoretical maximum on my hardware before I think about replacing my existing setup.
My current understanding is that it's not even possible, you always
have a min 2/3x slow down in the best case.
If you do sustained sequential write benchmark, and have a single
drive, then that drive ends up writing the data twice (journal + final
storage area) which with the seeks will more than divide by 2 the peak
perf of the drive. And since it's sequential, it will only write to 1
PG at a time (so not divided among several OSD).
Also AFAIU the OSD receiving the data will also have to send the data
to the other OSD in the PG and wait for them to say everything is
written before confirming the write, which slows it even more.
Cheers,
Sylvain
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