My Drobo desktop icons, x3, have rebooted themselves without any prompting from me.

I have x4, 1 TB drives.

I only had three icons on the desktop, not 4.

After the self check, only one icon has reappeared on my mac desktop.

In dashboard it tells me all four are there?

All of my imagery archive is on HD number three, but I cant get to it.

Any suggestions-please?

Are they visible in Disk Utility?