I'm sorry but I have to strongly disagree with ynguldyn, what they say might be true for other disk arrays but this is an EVA and I'm a through-and-through EVA-guy. We have dozens of them, all models and sizes, and there's literally zero benefit breaking up disk-groups into smaller units, they're designed that way and offer best performance when in one big block. In fact splitting disk-groups slows EVAs.
For example one of my newer 8400's has 16 shelves of 12 x 450Gb 15krpm FC disks, using iozone we tested it split into two disk-groups and it was 20% slower across the board of tests in this manner compared to a single disk group.
Also the array isn't broken into RAID types at the disk-group level, so it's not RAID10 for everything, individual vdisks (LUNs) have a particular RAID level but the disk-group itself only has the option to pre-allocated one or two hot standby disks (leave this at one by the way). This way you can give DB logs, MSDTC, Quorum etc. LUNS R10 and choose how your data and backup LUNs are setup based on your performance requirements (personally I use R10 for all data and R5 for backups but that's your choice). Oh and it's much quicker, and safer, to keep all your different DB data types in separate LUNS ok :)
If you have any follow-up questions regarding EVA's/XP's or other HP storage feel free to come back up me ok.