I don't know what's your budget, but this is a pretty good solution for the price:
http://store.apple.com/us/product/H...uctGroup=external&m.tsConnections=thunderbolt
It's not cheap, but 256GB of SSD through Thunderbolt is quite a nice external scratch disk.
Your Mac doesn't have USB 3.0 so otherwise you could get a USB 2.0 external hard drive for really cheap but performance will be considerably worse than the LaCie Thunderbolt SSD I pointed out (155 MB/s vs 30 MB/s).
Another solution would be to use a second internal drive in your optibay. It's more convenient, as long as you don't mind losing your optical drive.
thats kinda expensive.
SAsmung 840 pro + external TB enclosure would be cheaper.
I stand corrected.256GB Samsung 840 Pro ($269.99 on sale on Newegg) + Seagate GoFlex Thunderbolt adapter ($99.99) + Thunderbolt cable ($49.00) = $418.98.
Definitely not cheaper, plus that GoFlex adapter is a bit slower and it's going to be super fragile since it will simply be an internal drive with no enclosure. No USB 2.0/3.0 support as well when you want to connect to PCs.
MacBook Pro early 2011. Appears to be USB 2.0
Using PhotoShop CS6, trying to setup scratch drive.
Don't know if Thunderbolt is best solution or who offers best deal.
Any ideas?