I need to configure a RAID-1 on one SSD and one HDD. Both SSD and HDD has some preinstalled software, which I don't need so both can be fully wiped if that is any advantage.
My research so far lead me to the
--write-mostly option, which I understand that I should be using on the HDD such that read operations will get the full speed of the SSD.
But it is not clear to me, how to ensure the TRIM command is properly used.
I read warnings about mdadm writing to every sector of the device during setup leaving the SSD with no spare sectors regardless of any TRIM performed before setting up the raid.
Am I better off first creating the RAID degraded with the SSD as the only device and then adding the HDD, such that only the HDD gets written to?
What would I need to do to the SSD before setting up the RAID, such that any needed TRIM has been performed? The SSD has preinstalled software (that I don't need), which means I don't know which sectors has been previously written.
In case it is of any relevance, the SSD is 128GB and is in dmesg output mentioned as
SAMSUNG MZ7LF128HCP-00000, FXT0101Q by the ata layer and
SAMSUNG MZ7LF128 101Q PQ by the sd layer.