Disc failure detected with X-RAID2, now what?

Hello guys,

My ReadyNas Pro I noticed recently was in a resync mode. I only noticed because I was trying to connect to the NAS.

Now, my Volume Settings Config is:
RAID Level X-RAID2, 6 disks (with dual redundancy)

All 6 drives are occupied and disk5 is dead, according to my logs:
Mon Apr 23 06:59:21 PDT 2012 If the failed disk is used in a RAID level 1, 5, or X-RAID volume, please note that volume is now unprotected, and an additional disk failure may render that volume dead. If this disk is a part of a RAID 6 volume, your volume is still protected if this is your first failure. A 2nd disk failure will make your volume unprotected. It is recommended that you replace the failed disk as soon as possible to maintain optimal protection of your volume.
Mon Apr 23 06:59:21 PDT 2012 Disk failure detected.

Not terribly worried about my data since I have it backed up to CrashPlan account (I learned the HARD WAY about this), but wanted to know what happens next? Do I power down the system and take out the old drive, power up and it will start a sync?
Do I just hot swap it out?
When I turn off the computer, via the web GUI or the power button on the front (holding it down)?

Any advice would be much appreciated!