when I set this up I was tossing up between raid 5 and 3. I went with 5 in the end because it wasn't just video files that it was going to hold. Its always been slow. Max seems to be about 100 mb/s. I'm wondering if I'll get more joy if I re-stripe it as raid 10. I've had a horrible time with raid 10 before (file system errors got copied across the array and I lost a bunch of stuff), but that was with onboard raid.
Does anyone know if i'll get decent speeds with raid10 with this card?
That card is a couple generations old at this point but should provide the same performance as raid 10 was onboard. If the caching has been improved then you may get 300+ MB/s with 4 drives. However the raid 5 performance should be decent on that card. What drives are you using and how many?
7 x 2tb hitachi ultrastar sata3 (so I guess I'd need to buy another to do raid 10 ).
Yes you will need another drive for raid 10. 7 of those Drives in Raid 5 should definitely have far greater Raid 5 performance with the controller. Sounds like the cache settings were not set for write back.