I'm novice with Hitachi Unified Storage.
I've been reading "Hitachi Unified Storage Hardware Installation and Configuration Guide" (MK-91DF8273-17).
There are some questions about Hot Spare Drives.
1. Are Hot Spare Drives "global" spares?
"Global" means that any spare drive that has at least the same capacity as the drive to be replaced can be used in any array.
2. The chapter "Managing spares" says:
" If you enable Power Saving or Power Saving Plus, do not designate the following drives as spares:
• Drives #0 and #4 on a CBXSS/CBXSL/CBSS/CBSL Controller Box."
Why? Are there something special in Drives #0 and #4?