I generally use linux software md raid, but made the mistake of keeping IMSM "fakeraid" on a machine that came with it pre-configured. The fakeraid seeemed appealing because it worked seamlessly with both the bios and linux, which made it easier to configure (e.g., only install the bootloader once). Unfortunately, it seems to be impossible to set up a write intent bitmap with IMSM raid, and so my machine becomes painfully slow for 8 hours every time it crashes and reboots. (And unfortunately, I seem to be suffering a string of power outages.)
My question: is there an easy way to convert from IMSM fakeraid to linux software RAID without copying the data off somewhere (as I don't have another disk in the machine)? Alternatively, is there some way I haven't yet discovered to add a write intent bit map to fakeraid, so I don't have to rebuild the whole RAID array after every unexpected reboot?