I have a pfSense box with a 2-drive RAID-1 using
gmirror. Recently, a drive failed, and I replaced the drive, and the RAID-1 is now back to normal. But this incident also made me interested in setting up a 3-drive RAID-1, just for the extra redundancy.
Anyway, I figured it would be extremely easy to do this. Just attach a 3rd drive to the box and use
gmirror insert to add the new drive to the RAID.
So, I attached a new disk (of the same size as the other 2) via serial ATA to the pfSense box. Upon reboot, the disk appeared there in /dev as
So, before I attempted to add the new disk,
gmirror status showed the following:
Name Status Components mirror/pfSenseMirror COMPLETE ada0 (ACTIVE) ada1 (ACTIVE)
Then I typed:
gmirror insert pfSenseMirror /dev/ada2
After that, I checked the status again with gmirror status, and it showed:
Name Status Components mirror/pfSenseMirror DEGRADED ada0 (ACTIVE) ada1 (ACTIVE) ada2 (SYNCHRONIZING, 0%)
So it looked like everything was going well ...
But then, a few minutes later, I check gmirror status again, and now it shows:
Name Status Components mirror/pfSenseMirror DEGRADED ada0 (ACTIVE) ada2 (SYNCHRONIZING, 9%)
So... WTF? It looks like it kicked off drive
ada1 from the RAID for some reason.
So, what exactly is going on here? Does
gmirror inherently limit a RAID 1 to only 2 drives? Or did I do something wrong here?