As far as the hardware-managed VD's (arrays/LUN's) go: You can never "shrink" an array by either reducing the number of disks or the allocated space. Controllers do not support migrating TO or FROM nested RAID levels (10/50/50) ... for example, you cannot add two disks to a 4-disk RAID 10 either. If you plan to move to a RAID 10 (which I wholeheartedly support), then you will need to backup the current data and restore to the new array.
Our client has a T610 with an H700 integrated controller running as a VMware 5.5 host server   He currently has 6 drives in a single RAID5 array.  The current RAID5 LUN uses up all available space, although the actual allocated storage is a lot less. We're changing the function of the server significantly, adding a major database app.  As part of that, I want to add a couple more drives and convert the array to a pair of 4-drive RAID10 arrays.   I don't want to go into details of allocated space, LUN size, etc., here -- we can handle that.  My question is, if the allocated space fits target array size can I do this migration online?   Key questions: - can I reduce the size of the RAID5 LUN at all, or to anywhere approaching actual allocated space? - can I convert the RAID5 array to RAID10 -- again, assuming allocated space fits? - would I be better off first adding the additional drives and converting it to an 8-drive RAID10 array, and then splitting it into two 4-drive arrays? - what specific Dell server management software needs to be installed?   Or can this only be done at BIOS boot time? Obviously I'm going to do backups first! -- Ken
Support for on-line RAID5-10 migration on H700