I have a DL380 G5 (p411 SmartArray Controller) with a single loaded MSA60 (12x2TB SATA)and am purchasing a 2nd to cascaded as illustrated above. If I do this with identical disks (another 12x2TB SATA) can I apply RAID1+0 across the disks between the 2 enclosures for better I/O & resiliency?
If I/O performance is the key, you may not see tremendous gains. The MSA60 is capable of dual-domain configuration (MPIO), but it's also a 3G SAS unit (versus a 6G SAS). Also, you're using SATA drives, which will probably negotiate at 1.5Gbps. Resiliency may not be a big concern, as the MSA enclosures are well-built. If you RAID 1+0, you'll want to pair drives across enclosures, or perhaps skip the cascading and run the enclosures off of separate ports on the P411 controller.