if you look in VNX best practices document, there is actually a section for vertical provisioning. Other then some corner cases, it's not something that you MUST do and if you use virtual pools it does not matter anymore.
Hello,  Our current setup is as follows: VNX5100 1 x DPE (15 sas drives - 4 for OS) 1 x DAE (15 sas drives) 1 x DAE (2 sas drives)  We are using the array for a VMware server farm and was wondering what a recommended configuration could be to minimize downtime in case of a lost DAE: For example moving the disks: dpe - 10 disks dae - 9 disks dae - 9 disks  Then create some RAID groups that use disks from each tray????? I know by default the RAID groups take the disks from the same tray.  Thanks
Disk Array Layout