Hot spares are generally one for every 30 disks and this is not depend on where the 30 disks are located physically. So if have two DAE's with 30 600GB Fibre channel disks, then you would set aside one of those 30 disks for a Hot Spare. That one hot spare can be in either of the two DAE's.  Same for the STAT disks - one spare for every 30 disks.  I've attached a White Paper for hot sparing  glen
Hi,  We are running CX4-240 with 3 DAE.  2 of them are running FC Disk and the other one with SATA Disk.  The first FC HD DAE is created as RG while the other one is created as RAID 5 Storage Pool.  We would like to know is it possible to assign only 1 Hotspare 600GB Hotspare FC HD for both DAEs ?  Would it be a problem if one is RG while the other is Storage Pool ?  Currently, the DAE configured as Storage Pool gets 11 FC Disk (1 as Hot Spare).  We are going to add another 4 FC HD to that DAE as we are running out of space.  Since it is recommended to get FC Disk in multiple of 5, we intend to unbind the Hotspare on this DAE.  Your advice is sought.
Can we use 1 hotspare for 2 DAEs ?