Accusys ExaSAN A12S2-PS - Manual (Page 64)

4. How to Use
User Guide Page 4-13
4. Click on the drives to be added to the array. You can also click on Select all spare
drivers.
Note
Hot (Global) spare drive – When building an array, the hard
drives which are not defined will be used as spare drives for all
arrays defined within the controller. If a drive(s) in use fails, a
spare drive(s) will replace the faulty drive in the array and rebuild
automatically. One of the advantages of adopting hot spare
drive is to reduce the downtime.