I was playing around with software mirroring on a Windows 10 box with two SSD drives. There was no increase in read throughput between a single drive and RAID 1. I was under the impression RAID 1 should have increased the read throughput because there were two drives filling the pipe as opposed to just one but it didn't change much. Why wasn't RAID 1 better?
Writing to a RAID 1 drive will never be faster than writing to a single drive as all data needs to be written to both drives.
If implemented right, reading from RAID 1 might be twice as fast as reading from a single drive as each other chunk of data can be read from each other drive.
But the big advantage with RAID 1 is redundancy, if one drive goes bad you can still access all your data from the remaining drive.
How were you testing? A single sequential read is not going to be faster since both drives have to have their heads pass over the same data, even if the data is read from each drive in alternating chunks. That just means each drive will skip over half of the data and only return the other half, taking the same amount of time. Multiple read streams should see an increase however, since each drive can be reading an entirely different area of the disk.