Matthias Petermann <mp%petermann-it.de@localhost> writes: > in the meantime a few days have passed and after some back and forth I > have now found a parameterization in which my RAID-1 achieves very > satisfactory throughput rates (ca. 90 MB/s and more). I still can't > completely exclude that the hardware has a small damage, because I > think that I had tested the current configuration also at the > beginning, then with worse results. Anyway - for the sake of > completeness, here is a short summary of what finally led to > success. And of course thanks again for all the hints here in the > mailing list - that was a big help. Are you able to reproduce the bad performance? At a quick read, the setup instructions seem the same. Do you think it was just misalignment? > By the way: I have read in many places - including RAIDCTL(8) - that > it is not safe to create a partition or filesystem on the RAID device > until initialization with "-i" is 100% complete. If someone has a link > to a documentation that goes into this in more detail, I would be very > interested. Especially because I would like to understand what exactly > is so dangerous about it and under which circumstances - if any - > certain operations may be performed already during initialization. I > also think that it would be enough for me to know what exactly happens > on block level at -i. For the understanding of the source code I lack > the experience, and the very good paper under > > https://www.pdl.cmu.edu/RAIDframe/raidframebook.pdf > > does not seem to address this. To answer that you have to define safe. Two possible definitions are: If the system does not crash, you will end up with the right situation after newfs and '-i' are both complete. If the system does crash/losepower in the middle, you will still have a consisten state with no data loss. If there is a failure of one of the disks, then you can still use the filesystem and get back the bits you put on it My guess is that if you care about the first property, things are ok, and if you care about the second, things are probably ok, and if you care about the third, you have to wait until the raid set is initialized before writing data. So I'd say newfs before init finishes is ok, but don't expect to have raid protection. I'd be inclined to just wait.
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