If you are not worrying about capacity at this point, i'd go with the 4+1 R5 setups. For reasons already discussed by dynamox: rebuild time (disk failures WILL happen, so let's limit the time your at risk for a dual disk failure and also have lower performance) and a proper stripe size of 4x64KB = 256KB (giving a higher chance for full stripe writes, which lower back-end load significantly).  Depending on how many LUNs you prefer to assign to the host, either assign them directly to the host(s) or use MetaLUNs to stripe across the RAID groups to take advantage of the disk count. Seeing you have 4 DAE's, if you place them on different busses, you could stripe your MetaLUN across DAE's. If you take the MetaLUN approach with 4+1 R5 RGs, you can keep your Element Size Multiplier in the MetaLUN config tab on 4.
If I have a DAE with 15 drives, is it more performant to create a single Raid-5 14+1 or 3x Raid-5 4+1 raid groups? This is for a database application which will consume the entire DAE for this single app. Aside from the fact that having 3 LUNs provides more host-paths than a single LUN does, is there any plus or minus to using a large raid group rather than multiple smaller ones? Im already aware that 3 smaller raid groups are a bit less space efficient, not worried about volume, only about performance at this point. This DB is a large block, fairly random access with 512K block size. Ive configured the Clariion with small read cache and large as possible write cache and lowered the watermarks to 40/60... The database spans 4 DAE's so my LUN config would be 4x (14+1) luns or 12x (4+1) luns. I would be interested in knowing why a particular config is chosen as well. Thanks, Ron
Which Raid-5 configuration is more performant?