Because I'm always struggling with my photo libraries and other large projects I'm looking for a portable raid. I'm using SSD's in a USB enclosure, but have had some drive errors that caused me quite a lot of pain so would like to have something that's a little safer.
I found the Drobo mini and the Western Digital My Passport Pro, are there any others I need to take a look at? Thunderbolt connection is a plus.
Hey there No-Me,
WD My Passport Pro is indeed a good portable RAID solution.
I could suggest checking a couple of more Thunderbolt RAID solutions. They are not as compact as the My Passport but are still portable/movable, work great and support RAID0, RAID1 and JBOD.
WD My Book Thunderbolt Duo:
http://www.wdc.com/en/products/products.aspx?id=630#Tab3 (this drive is formatted for Mac, with RAID0 it can reach up to 300MB/s, works at 10 Gb/s and you have the opportunity to swap the drives in case either of them fail).
WD My Book VelociRaptor Duo:
http://www.wdc.com/en/products/products.aspx?id=860#Tab3 (has the same features as the Thunderbolt Duo but comes with 2 10,000 rpm WD VelociRaptor drives, boosting speed even more).
You can always get a 2-bay enclosure, put 2 similar drives and configure them in RAID if you don't want to use a preconfigured and prebuilt device.

Do have in mind that RAID (even Mirror types of RAID) is not a backup itself. It only offers redundancy if it's the only place you store that data. I would suggest backing up that data elsewhere if you are using those portable drives as main drives and not as a backup.
You could always go for a NAS solution.
Hope this helps,
Captain_WD.