- Annoyance
Write performance is reduced whilst "Clearing in progress".
Possible optimisation not being used?
Whilst a drive is "clearing" (4) it has the same effect as "Tunable (md_write_method)" being changed from "reconstruct write" to "read/modify/write"...
... i.e. I see reads on both parity drives (1) at the same MB/s rate as the reads from the source drive (2) and writes to one array drive (3).
When a drive is not "clearing" the write performance is as expected, and parity drives are not read from.
I can imagine a test where if not all drives can be read the "md_write_method" mode changes from "reconstruct write" to "read/modify/write" - but perhaps drives being cleared should be ignored?