RAID Group with different capacity disks

You will only get the lowest capacity of all the disks in this scenario. Means you will get raw capacity of 146gb from the 300gb disk. The remaining capacity is wasted.

As previously stated, the answer is Yes.

The total capacity of the RAID group you've described would be: 1202.83GB as a RAID 5 (9+1), 1069.18GB as 2x RAID 5 (4+1), or 1069.18 GB as a RAID 6 (8+2). The 2x RAID 5 4+1 in a MetaLUN or the 8+2 are the recommended configuration. (See Best Practices.)

It is highly recommended that RAID groups be created from the same type (FC, SAS, or SATA), speed (15K rpm, 10K rpm, and 7.2K rpm), and capacity drives.

Having like drives in a RAID group ensures the highest usable capacity, high reliability, and consistent performance. For example, if you are mixing drives of different capacities in a RAID group, then the capacity of the smallest bound drive will be used from each disk in the group to makeup the RAID group¿s overall capacity. The full capacity of the RAID group's larger disks will be unused. Likewise, mixing higher rpm drives with lower rpm drives lowers the overall RAID group performance. I/O requests to the slower drives will take longer to complete than I/O to faster drives. This will increase the average RAID group response time and the response time of multi-drive I/O.

Information on RAID groups and RAID group performance can be found in the Logical Storage Objects section of the EMC CLARiiON Storage System Fundamentals for Performance and Availability. This document is available on PowerLink. (The above section was excerpted from the forthcoming Revision 1.1.)