After looking into this, you will lose a little space but when you add that 8th drive into the array you will be able to convert it to a RAID 10 with no issues.
I currently have an MD3200 with 8 of 12 slots populated (always fill all slots when you buy, people!) The size and quantity of drives was chosen early on in my project when I had intended to use RAID5. I'm realizing now that I would be better off with RAID10. 7 of the 8 disks are in a RAID5 Disk Group (the 8th is a global hot spare). Two questions: -Is it even possible for the MD3200 to migrate from RAID 5 to RAID 10? When I right click the disk group in MDSM and select Change->RAID Level->RAID 1 or 10... is not grayed out, but I have data on the array now and I can't test it. -Assuming it is possible, obviously going from RAID 5 to RAID 10 with the same number of disks would not be possible, since RAID 10 would have a lower capacity (unless it's capable of doing this as long as less than the capacity of the RAID10 is unallocated.. not sure). I know since I am using 7 disks and have 1 hot spare, I would need to add at least one more to continue having a hot spare (how necessary is this with RAID 10, anyway?). Is there any other requirement I should know about? Last time I checked with my rep there were no additional SAS drives available for sale, so this is all assuming I'll be able to buy more some day (joke).
MD3200 - 8 disk RAID5 to ? disk RAID 10 possible?