When a disk fails and you have a free Hot Spare, the Hot Spare will take over for the failed disk - it will "rebuild" to the hot spare if the raid type that the old disk was using is either a Raid5 or Raid6 and when that is finished, the hot spare will operate the same as the failed disk. During the rebuild, performance may be lower but will return to normal once the rebuild is finished - in the Event Logs you will see messages about this.  The raid group that the failed disk belongs to will be faulted until the failed disk is replaced. Once you replace the failed disk the hot spare will "equalize" to the new disks (basically a copy operation). Then the new disk will take over, the hot spare will be released as a free hot spare and the raid group will changed from faulted to good.  If you have a service contract with EMC, just opened a service request with EMC to either send you a replacement disk or will replace the disk for you (depending on the level of service).  glen
Hi, complete newbie here. My engineer has moved on to another company and storage was not my responsibility before. We have a cx4-120 and apparently a disk went bad last week (engineer did not have any notifications set up so only now becoming aware of issue). I can see where it says the bad disk is "removed" and where it says a hot spare is "replacing" that bad disk. But what I don't know is whether a rebuild of data starts automatically or do I have to tell it to do something?  We are definitely seeing issues with some VMs so I get the feeling I need to take action somewhere but don't know where.  Any help is much appreciated. thanks. If I've got this posted in the wrong place, please let me know. thanks.
CX4-120 Need help with hot spare