Areca Support: Dear Sir, the only difference is in JBOD mode, controller configure all drives as passthrough disk. in RAID mode, you have to configure passthrough disk by yourself in RAID mode

in other words, you can use raid with passthrough disks at saem time in RAID mode but JBOD mode not.

Me: So does that mean if I use passthrough, I am not protected by the cache/battery backup? I ask because there is an option for cache mode when creating a passthrough disk. i.e. Write-Back or Write-Through

So 'passthrough' means that the controller lets the OS see the physical disks just as they are, but with an invisible cache in between that buffers operations. This way there is no advantage of the onboard XOR engine, but you do profit from the intelligent cache, which is the most important anyway imho.

JBOD mode is at a disadvantage because in this mode the OS sees one large drive, and is not able to stripe the data to multiple disks, not taking advantage of the fact that you have multple spindles available. Makes sense to me :).

I must admit, I do like these results. Very promising.

Further tests would be using an SSD for the ZIL, testing linux and NT, etc. But let's not go there ;).