Making a Mirror

Yes.

here are the steps:
"convert" drive A to SoftRAID
Initialize drive B with SoftRAID
"Convert the volume on drive A to Mirror, select the new disk
It will convert and rebuild in the background.
It will be a Mirror from then on.

(we recommend you certify any disks you want to use in a RAID volume, so you know it is reliable before using it. Certify is a data-destructive test however.)

If I do that I get:

ERROR CONVERTING VOLUME

There is not a SoftRAID volume with free space available. You need to have 1 SoftRAID disk with free space available for this conversion.

Yes.

here are the steps:
"convert" drive A to SoftRAID
Initialize drive B with SoftRAID
"Convert the volume on drive A to Mirror, select the new disk
It will convert and rebuild in the background.
It will be a Mirror from then on.

(we recommend you certify any disks you want to use in a RAID volume, so you know it is reliable before using it. Certify is a data-destructive test however.)

Look in the disk tiles.
Is the second disk the same size or larger than the Drive A? (Even 1 byte smaller means this won't work without reducing the source volume's size)
Did you initialize the second disk with SoftRAID?
Did you create a volume on it? (don't!)

Okay. I was able to create a mirror with Drive A & B. I noticed that I do not see Drive B anywhere in Finder. Is this normal? Is there a way for me to see the contents of Drive B with Finder?

I was able to split the RAID volume and determine that both Drive A & B are identical. How does SoftRAID determine that the data is 100% identical between the two?

Now that I split the RAID volume is there a way to reconnect them? I was unable to do that, but did create another RAID volume.

If I do that I get:

ERROR CONVERTING VOLUME

There is not a SoftRAID volume with free space available. You need to have 1 SoftRAID disk with free space available for this conversion.

Yes.

here are the steps:
"convert" drive A to SoftRAID
Initialize drive B with SoftRAID
"Convert the volume on drive A to Mirror, select the new disk
It will convert and rebuild in the background.
It will be a Mirror from then on.

(we recommend you certify any disks you want to use in a RAID volume, so you know it is reliable before using it. Certify is a data-destructive test however.)

A Mirror volume is a single volume with multiple disks making up the volume. The secondary disks will never show up in Finder. That is how a mirror works.

A Mirror is not the same as, for example, file synchronization, where files are copied from one volume to another. In that case, there are two distinct volumes to the file system, and the data is "synchronized" between them.

A Mirror volume is comprised of a Primary ("gold master") disk and one or more secondary disks. Once a mirror is rebuilt, the secondary will contain exactly the same information as the primary. However, a secondary disk cannot "mount", it is always hidden. If the primarydisk dies, then a secondary disk is converted to a primary disk of a new volume and mounted as a separate volume. It cannot be "merged" with the prior disk, as there is no way for SoftRAID to know which contains the correct data.

In short, a Mirror is a single volume, that mounts as a standard volume on the desktop. OS X does not see the various parts of the mirror, it only sees a volume that mounts. All writes are copied to all disks, and hence any read can be read from all disks to improve performance.

SoftRAID automatically takes care of ensuring the disks are identical. We have a validate function, which will ensure the volume is made of identical parts if you want to confirm SoftRAID disks are identical. But SoftRAID knows what to do, you do not have to worry about this.

Once you split a mirror, you can only merge these two independent volumes by deleting one of the volumes, then "Add Secondary Disk".

We have more explanation on how Mirrors work on this page:
https://srforums.wpengine.com/pages/features/raid_levels.html#raid1