I am currently working on creating a 48TB linux storage server that I eventually will make into an iSCSI target. What i'm stuck on right now is should I implement a single 24 port RAID card and create a single RAID 5 array to use for data storage OR should I implement 3 8-port RAID cards, create 3 RAID 5 arrays, and software RAID the 3 arrays together (RAID 0) so it shows up as one big disk (md0). Will I see any performance improvements by doing the second option? Will there be less parity calculation time since it is being spread across 3 arrays? ANY information is greatly appreciated.
Personally I would go with the single 24port RAID card, but this is also probably the more expensive of the two options. First off from a performance standpoint, with the single 24 port solution you can use the hardware RAID controller/proc for the XOR calcs rather than the system processor. From a reliability standpoint I tend to like hardware RAID better, and with 3 separate cards you have 3 potential things to fail versus 1. That being said, you should always have a spare controller and a spare 24 port would cost much more than a spare 8 port.