The document is suggesting 14 RAID 0s. The spare drive is not  a hot spare, it is just an extra/spare drive. You can use it for whatever you like, it is unused in the example configuration in that document. The document is focused on availability and performance. It is likely recommending RAID 0s instead of pass-through/non-RAID because of performance concerns. The controller will only use features like write-back for a RAID disk. If the disk is in a non-RAID mode it will not use controller write cache. Thanks
We have purchased Dell PowerEdge R730xd for Exchange services and are looking to best practices document for Exchange 2016 implementation by Dell. We are following the dell reference architecture for 5000 mailboxes Exchange 2016 environment. The document is also attached for reference with this post. Servers are R730XD with 16 x 8TB 7200RPM and 2 x 1.2TB SAS 10K drives.  Server have 14 x 8 TB drives for Exchange DB and Logs and 2 Spare drives ( 16 drives in total). In storage architecture it says (Fourteen independent Raid 0 disks can be used to store copies of Exchange databases. A Raid Controller Can be used to create independent Raid 0 volumes by using internal drives." It says to create a 14 x 8TB RAID-0 for database and logs?  Q: does this mean a single 14x8TB raid 0 group or they mean 14 Raid (Raid 0) group and each Raid 0 with single disk? For reference please check page 38 of Storage Architecture section in attached document. Q: If they mean to create one Raid0 group with 14 drives then it says to keep one drive for restore LUN? From where we will restore a LUN when, on a drive failure we will lose the entire raid 0 group?   Q: keep one hot spare - that’s understandable  Will be grateful if someone who has knowledge of these servers and storage layout shed some light and provide guidance  Thanks and regards  
Exchange 2016 Best Practices by Dell